Looking for on how to bundle a library using webpack, the library link is : https://github.com/InteractiveAdvertisingBureau/Consent-String-SDK-JS/
I tried the following structure :
> /dist
> - index.html
> /src
> - index.js
> package.json
> webpack.config.js
content of :
index.html
<!doctype html>
<html>
<head>
<title>Hello Webpack</title>
</head>
<body>
<script src="bundle.js"></script>
<script type="text/javascript">
var consentData = new CSLib();
console.log('euconsent : '+consentData);
</script>
</body>
</html>
index.js
require('consent-string');
webpack.config.js :
const path = require('path')
module.exports = {
entry: './src/index.js',
output: {
filename: 'bundle.js',
library: 'CSLib',
libraryTarget: 'umd',
path: path.resolve(__dirname, 'dist')
}
}
after runnning npm run build the bundle.js file is generated
but when trying to access the index file, an error is occured in the browser, say that CSlib is undefined.
please your help, I would really appreciate it.
First of all, you need to bind the result of require('consent-string'); to something. I do not know the library but looking at their npm page you should be able to do the following.
const { ConsentString : CSLib} = require('consent-string');
However even if you do that it would not work due to some details of how webpack actually works. Basically each module, or rather file, is executed inside it's own scope and they do not leak to the global context. How does it do this? Allow me to demonstrate.
Webpack internals basics
Let's start with the following example file that imports jquery, prints "test", and exports something.
const $ = require('jquery');
console.log("test");
export function test() {
console.log("test");
}
Run webpack on this file and open bundle.js. You will find that it starts by defining a function as follows: function(modules). This is webpacks bootstrap function. If you really count all the brackets you will find that it is defined and then immediately called with an array of functions with the following signature function(module, exports, __webpack_require__). Each function in this array represents a module, or rather a file, that webpack has included in the bundle. You will find a module 0 which is generated by webpack. It looks like this:
/* 0 */
/***/function(module, exports, __webpack_require__) {
module.exports = __webpack_require__(1);
/***/ }
All it does is call __webpack_require__(1). So what does that do? __webpack_require__ is passed in as an argument to the module function that we are in but if you look inside the bootstrap function you will find that it is defined there. It works as follows
If the module with the given id (the id being an index into the array of modules that we discussed earlier) has been "installed" simply return that modules exported properties. A module has been installed if it has an entry in the installedModules array.
Otherwise, define a new module object (stores the modules id, if it has been loaded yet and it's exports) then call the module function with some arguments that I will discuss later.
Mark the module as loaded, add the module object to installedModules, and return its exports property (we will see how exports is populated in a minute).
Now let's look at how webpack has transformed the code we gave it. It can be found in module 1 (which is called from module 0 remember) and looks as follows (there might be some bookkeeping stuff in there too but I will ignore it, it's there for compatibility reasons I think):
var $ = __webpack_require__(2);
console.log("test");
function test() {
console.log("test");
}
exports.test = test;
The first line is var $ = __webpack_require__(2); This we have already discussed. It just imports jquery which is module 2 (which is why module 2 takes up most of the file as it includes all of jquery).
Then we have console.log("test");. Nothing has changed from the code we passed in.
But the function we exported has been split into two statements. First the function is defined and then it is added to exports as a property. The exports object is passed in by __webpack_require__ and it represents the properties that the module exports. It is stored in installedModules in a module object. Remember that any subsequent call to __webpack_require__ will just return the exports property of this module object.
tldr: Webpack will transform all of those fancy module based operations into calls to __webpack_require__ for imports and assignments to exports for export statements. This gives the illusion that every module exists in it's own little world.
What this means to you
Since each module is run inside it's own scope you will need to group the code that uses require('consent-string'); with the require statement. In conclusion your index.js should look like this:
const { ConsentString : CSLib} = require('consent-string');
var consentData = new CSLib();
console.log('euconsent : '+consentData);
Related
What is the purpose of Node.js module.exports and how do you use it?
I can't seem to find any information on this, but it appears to be a rather important part of Node.js as I often see it in source code.
According to the Node.js documentation:
module
A reference to the current
module. In particular module.exports
is the same as the exports object. See
src/node.js for more information.
But this doesn't really help.
What exactly does module.exports do, and what would a simple example be?
module.exports is the object that's actually returned as the result of a require call.
The exports variable is initially set to that same object (i.e. it's a shorthand "alias"), so in the module code you would usually write something like this:
let myFunc1 = function() { ... };
let myFunc2 = function() { ... };
exports.myFunc1 = myFunc1;
exports.myFunc2 = myFunc2;
to export (or "expose") the internally scoped functions myFunc1 and myFunc2.
And in the calling code you would use:
const m = require('./mymodule');
m.myFunc1();
where the last line shows how the result of require is (usually) just a plain object whose properties may be accessed.
NB: if you overwrite exports then it will no longer refer to module.exports. So if you wish to assign a new object (or a function reference) to exports then you should also assign that new object to module.exports
It's worth noting that the name added to the exports object does not have to be the same as the module's internally scoped name for the value that you're adding, so you could have:
let myVeryLongInternalName = function() { ... };
exports.shortName = myVeryLongInternalName;
// add other objects, functions, as required
followed by:
const m = require('./mymodule');
m.shortName(); // invokes module.myVeryLongInternalName
This has already been answered but I wanted to add some clarification...
You can use both exports and module.exports to import code into your application like this:
var mycode = require('./path/to/mycode');
The basic use case you'll see (e.g. in ExpressJS example code) is that you set properties on the exports object in a .js file that you then import using require()
So in a simple counting example, you could have:
(counter.js):
var count = 1;
exports.increment = function() {
count++;
};
exports.getCount = function() {
return count;
};
... then in your application (web.js, or really any other .js file):
var counting = require('./counter.js');
console.log(counting.getCount()); // 1
counting.increment();
console.log(counting.getCount()); // 2
In simple terms, you can think of required files as functions that return a single object, and you can add properties (strings, numbers, arrays, functions, anything) to the object that's returned by setting them on exports.
Sometimes you'll want the object returned from a require() call to be a function you can call, rather than just an object with properties. In that case you need to also set module.exports, like this:
(sayhello.js):
module.exports = exports = function() {
console.log("Hello World!");
};
(app.js):
var sayHello = require('./sayhello.js');
sayHello(); // "Hello World!"
The difference between exports and module.exports is explained better in this answer here.
Note that the NodeJS module mechanism is based on CommonJS modules which are supported in many other implementations like RequireJS, but also SproutCore, CouchDB, Wakanda, OrientDB, ArangoDB, RingoJS, TeaJS, SilkJS, curl.js, or even Adobe Photoshop (via PSLib).
You can find the full list of known implementations here.
Unless your module use node specific features or module, I highly encourage you then using exports instead of module.exports which is not part of the CommonJS standard, and then mostly not supported by other implementations.
Another NodeJS specific feature is when you assign a reference to a new object to exports instead of just adding properties and methods to it like in the last example provided by Jed Watson in this thread. I would personally discourage this practice as this breaks the circular reference support of the CommonJS modules mechanism. It is then not supported by all implementations and Jed example should then be written this way (or a similar one) to provide a more universal module:
(sayhello.js):
exports.run = function() {
console.log("Hello World!");
}
(app.js):
var sayHello = require('./sayhello');
sayHello.run(); // "Hello World!"
Or using ES6 features
(sayhello.js):
Object.assign(exports, {
// Put all your public API here
sayhello() {
console.log("Hello World!");
}
});
(app.js):
const { sayHello } = require('./sayhello');
sayHello(); // "Hello World!"
PS: It looks like Appcelerator also implements CommonJS modules, but without the circular reference support (see: Appcelerator and CommonJS modules (caching and circular references))
Some few things you must take care if you assign a reference to a new object to exports and /or modules.exports:
1. All properties/methods previously attached to the original exports or module.exports are of course lost because the exported object will now reference another new one
This one is obvious, but if you add an exported method at the beginning of an existing module, be sure the native exported object is not referencing another object at the end
exports.method1 = function () {}; // exposed to the original exported object
exports.method2 = function () {}; // exposed to the original exported object
module.exports.method3 = function () {}; // exposed with method1 & method2
var otherAPI = {
// some properties and/or methods
}
exports = otherAPI; // replace the original API (works also with module.exports)
2. In case one of exports or module.exports reference a new value, they don't reference to the same object any more
exports = function AConstructor() {}; // override the original exported object
exports.method2 = function () {}; // exposed to the new exported object
// method added to the original exports object which not exposed any more
module.exports.method3 = function () {};
3. Tricky consequence. If you change the reference to both exports and module.exports, hard to say which API is exposed (it looks like module.exports wins)
// override the original exported object
module.exports = function AConstructor() {};
// try to override the original exported object
// but module.exports will be exposed instead
exports = function AnotherConstructor() {};
the module.exports property or the exports object allows a module to select what should be shared with the application
I have a video on module_export available here
When dividing your program code over multiple files, module.exports is used to publish variables and functions to the consumer of a module. The require() call in your source file is replaced with corresponding module.exports loaded from the module.
Remember when writing modules
Module loads are cached, only initial call evaluates JavaScript.
It's possible to use local variables and functions inside a module, not everything needs to be exported.
The module.exports object is also available as exports shorthand. But when returning a sole function, always use module.exports.
According to: "Modules Part 2 - Writing modules".
the refer link is like this:
exports = module.exports = function(){
//....
}
the properties of exports or module.exports ,such as functions or variables , will be exposed outside
there is something you must pay more attention : don't override exports .
why ?
because exports just the reference of module.exports , you can add the properties onto the exports ,but if you override the exports , the reference link will be broken .
good example :
exports.name = 'william';
exports.getName = function(){
console.log(this.name);
}
bad example :
exports = 'william';
exports = function(){
//...
}
If you just want to exposed only one function or variable , like this:
// test.js
var name = 'william';
module.exports = function(){
console.log(name);
}
// index.js
var test = require('./test');
test();
this module only exposed one function and the property of name is private for the outside .
There are some default or existing modules in node.js when you download and install node.js like http, sys etc.
Since they are already in node.js, when we want to use these modules we basically do like import modules, but why? because they are already present in the node.js. Importing is like taking them from node.js and putting them into your program. And then using them.
Whereas Exports is exactly the opposite, you are creating the module you want, let's say the module addition.js and putting that module into the node.js, you do it by exporting it.
Before I write anything here, remember, module.exports.additionTwo is same as exports.additionTwo
Huh, so that's the reason, we do like
exports.additionTwo = function(x)
{return x+2;};
Be careful with the path
Lets say you have created an addition.js module,
exports.additionTwo = function(x){
return x + 2;
};
When you run this on your NODE.JS command prompt:
node
var run = require('addition.js');
This will error out saying
Error: Cannot find module addition.js
This is because the node.js process is unable the addition.js since we didn't mention the path. So, we have can set the path by using NODE_PATH
set NODE_PATH = path/to/your/additon.js
Now, this should run successfully without any errors!!
One more thing, you can also run the addition.js file by not setting the NODE_PATH, back to your nodejs command prompt:
node
var run = require('./addition.js');
Since we are providing the path here by saying it's in the current directory ./ this should also run successfully.
A module encapsulates related code into a single unit of code. When creating a module, this can be interpreted as moving all related functions into a file.
Suppose there is a file Hello.js which include two functions
sayHelloInEnglish = function() {
return "Hello";
};
sayHelloInSpanish = function() {
return "Hola";
};
We write a function only when utility of the code is more than one call.
Suppose we want to increase utility of the function to a different file say World.js,in this case exporting a file comes into picture which can be obtained by module.exports.
You can just export both the function by the code given below
var anyVariable={
sayHelloInEnglish = function() {
return "Hello";
};
sayHelloInSpanish = function() {
return "Hola";
};
}
module.export=anyVariable;
Now you just need to require the file name into World.js inorder to use those functions
var world= require("./hello.js");
The intent is:
Modular programming is a software design technique that emphasizes
separating the functionality of a program into independent,
interchangeable modules, such that each contains everything necessary
to execute only one aspect of the desired functionality.
Wikipedia
I imagine it becomes difficult to write a large programs without modular / reusable code. In nodejs we can create modular programs utilising module.exports defining what we expose and compose our program with require.
Try this example:
fileLog.js
function log(string) { require('fs').appendFileSync('log.txt',string); }
module.exports = log;
stdoutLog.js
function log(string) { console.log(string); }
module.exports = log;
program.js
const log = require('./stdoutLog.js')
log('hello world!');
execute
$ node program.js
hello world!
Now try swapping ./stdoutLog.js for ./fileLog.js.
What is the purpose of a module system?
It accomplishes the following things:
Keeps our files from bloating to really big sizes. Having files with e.g. 5000 lines of code in it are usually real hard to deal with during development.
Enforces separation of concerns. Having our code split up into multiple files allows us to have appropriate file names for every file. This way we can easily identify what every module does and where to find it (assuming we made a logical directory structure which is still your responsibility).
Having modules makes it easier to find certain parts of code which makes our code more maintainable.
How does it work?
NodejS uses the CommomJS module system which works in the following manner:
If a file wants to export something it has to declare it using module.export syntax
If a file wants to import something it has to declare it using require('file') syntax
Example:
test1.js
const test2 = require('./test2'); // returns the module.exports object of a file
test2.Func1(); // logs func1
test2.Func2(); // logs func2
test2.js
module.exports.Func1 = () => {console.log('func1')};
exports.Func2 = () => {console.log('func2')};
Other useful things to know:
Modules are getting cached. When you are loading the same module in 2 different files the module only has to be loaded once. The second time a require() is called on the same module the is pulled from the cache.
Modules are loaded in synchronous. This behavior is required, if it was asynchronous we couldn't access the object retrieved from require() right away.
ECMAScript modules - 2022
From Node 14.0 ECMAScript modules are no longer experimental and you can use them instead of classic Node's CommonJS modules.
ECMAScript modules are the official standard format to package JavaScript code for reuse. Modules are defined using a variety of import and export statements.
You can define an ES module that exports a function:
// my-fun.mjs
function myFun(num) {
// do something
}
export { myFun };
Then, you can import the exported function from my-fun.mjs:
// app.mjs
import { myFun } from './my-fun.mjs';
myFun();
.mjs is the default extension for Node.js ECMAScript modules.
But you can configure the default modules extension to lookup when resolving modules using the package.json "type" field, or the --input-type flag in the CLI.
Recent versions of Node.js fully supports both ECMAScript and CommonJS modules. Moreover, it provides interoperability between them.
module.exports
ECMAScript and CommonJS modules have many differences but the most relevant difference - to this question - is that there are no more requires, no more exports, no more module.exports
In most cases, the ES module import can be used to load CommonJS modules.
If needed, a require function can be constructed within an ES module using module.createRequire().
ECMAScript modules releases history
Release
Changes
v15.3.0, v14.17.0, v12.22.0
Stabilized modules implementation
v14.13.0, v12.20.0
Support for detection of CommonJS named exports
v14.0.0, v13.14.0, v12.20.0
Remove experimental modules warning
v13.2.0, v12.17.0
Loading ECMAScript modules no longer requires a command-line flag
v12.0.0
Add support for ES modules using .js file extension via package.json "type" field
v8.5.0
Added initial ES modules implementation
You can find all the changelogs in Node.js repository
let test = function() {
return "Hello world"
};
exports.test = test;
I am trying to use require.js to load my modules dependencies and so far it is working, but I have a doubt. I've created a little function to test the modules and placed it in a file called panelTest.js:
define(['./panel/View', './panel/TitleView'], function(View, TitleView) {
return function test(container) {
// main view
var panel = new View(container, 'main');
var panelTitle = new TitleView(panel.getContainer(), 'main-title');
panelTitle.setTitle('Properties Panel');
//panelTitle.addCss('pjs-panelTitle');
panel.addView(panelTitle);
// sections
var top = new View(panel.getContainer(), 'top');
panel.addView(top);
var middle = new View(panel.getContainer(), 'middle');
panel.addView(middle);
var bottom = new View(panel.getContainer(), 'bottom');
panel.addView(bottom);
};
});
In the html that uses the modules I included this script tag as shown in the require.js documentation to load panelTest.js.
<script data-main="panelTest.js"
src="require.js"></script>
My question is how can I call the test function from outside the module, since the container parameter it is supposed to come from outside the module.
You have to access the module through the appropriate channels provided by RequireJS. You could do it like this in a script tag that appears after the one that loads RequireJS:
require(['panelTest'], function (panelTest) {
panelTest(/* some value */);
});
Given the code you show, your panelTest module does not seem to really make sense as a "main module" so I would not put it as data-main.
If you want to use it from anther module, put the module in its own file and define it like this:
define(['panelTest'], function (panelTest) {
panelTest(/* some value */);
});
Project Structure
root
wwwroot <-- files under this location are static files public to the site
css
lib
bootstrap/js/bootstrap.js
jquery/js/jquery.js
knockout/knockout.js
requires/require.js
scripts
modules ┌───────────────┐
global.js <--│ Built modules │
dropdown.js └───────────────┘
modules
global.js ┌────────────────┐
dropdown <--│ Source modules │
dropdown.js └────────────────┘
gruntfile.js
global.cs Contents (pre-built version at ~/modules/global.js)
require.config({
baseUrl: "scripts/modules",
paths: {
jquery: "../../lib/jquery/js/jquery",
bootstrap: "../../lib/bootstrap/js/bootstrap",
knockout: "../../lib/knockout/knockout"
},
shims: {
bootstrap: {
deps: ['jquery']
}
},
});
define(function (require) {
var $ = require('jquery');
var ko = require('knockout');
var bootstrap = require('bootstrap');
});
dropdown.js Contents (pre-built version at ~/modules/dropdown.js)
define(function () {
console.log('dropdown initialized');
return 'foo';
});
HTML Page
Contains this script tag in the <head> of the page for loading requires config:
<script src="~/lib/requirejs/require.js" data-main="scripts/modules/global"></script>
In the body of the HTML page, I have the following:
<script>
require(['global'], function () {
require(['dropdown'], function (dropdown) {
console.log(dropdown);
});
});
</script>
Issue
The dropdown callback is undefined instead of the expected "foo" string that I'm returning from the defined module.
In fact, the console does not contain a log item for "dropdown initialized" either. This makes me believe the module is not being invoked somehow? However, it's strange the dropdown.js is present in F12 debugger as a script loaded into the page. Therefore, requires did make a call to load it, but did not run the contents of the define?
Noteworthy mentions
I'm using r.js to optimize and build. Both global.js and dropdown.js are processed over.
The name assigned to the dropdown module by r.js processing is "modules/dropdown/dropdown.js". I'm unsure if I should be using this somehow, or if I'm referring to the module correctly as just dropdown and relying on my baseUrl config having the correct path.
Edit #1
I have added the r.js build configuration used with grunt per commenter request. In conjunction, I updated the file structure to include the overall project structure, instead of just the runtime public wwwroot structure.
The r.js process will compile built forms of global.js + other modules in ~/wwwroot/scripts/modules from the source location ~/modules in summary.
function getRequireJsConfiguration() {
var baseUrl = './';
var paths = {
jquery: "wwwroot/lib/jquery/js/jquery",
bootstrap: "wwwroot/lib/bootstrap/js/bootstrap",
knockout: "wwwroot/lib/knockout/knockout"
};
var shims = {
bootstrap: {
deps: ['jquery']
}
};
var optimize = 'none';
var configuration = {};
var jsFilePaths = grunt.file.expand('modules/**/*.js');
jsFilePaths.forEach(function (jsFilePath) {
var fileName = jsFilePath.split('/').pop();
if (configuration[fileName]) {
throw 'Duplicate module name conflict: ' + fileName;
}
configuration[fileName] = {
options: {
baseUrl: './',
name: jsFilePath,
out: 'wwwroot/scripts/modules/' + fileName,
paths: paths,
shims: shims,
optimize: optimize,
exclude: ['jquery', 'knockout', 'bootstrap']
}
};
});
configuration['global'] = {
options: {
baseUrl: './',
name: 'modules/global.js',
out: 'wwwroot/scripts/modules/global.js',
paths: paths,
shims: shims,
optimize: optimize,
}
};
return configuration;
}
Edit #2
Thought it'd be a good idea to include the versions of requirejs packages I'm using:
requirejs: 2.1.15
grunt-contrib-requirejs: 0.4.4
Thanks.
The name assigned to the dropdown module by r.js processing is "modules/dropdown/dropdown.js". I'm unsure if I should be using this somehow, or if I'm referring to the module correctly as just dropdown and relying on my baseUrl config having the correct path.
In a sense, yes, you should be using that full path. That's what Require refers to as the module id - "modules/dropdown/dropdown" (if the .js in the above output was real, I suggest stripping that extension in the "name" config. .js is assumed by RequireJS, you don't want that string in your module ids). The basePath is used, when given IDs, to transform some unknown ID to a file path (e.g. 'bootstrap' id -> (applying path config) -> '../../lib/bootstrap/js/bootstrap' -> (applying base URL) -> 'scripts/modules/../../lib/bootstrap/js/bootstrap').
Really, though, just allowing r.js to concatenate everything into one file
is the preferred way to go. You could use the include option to include modules un-referenced by global.js in with the optimized bundle, too ( https://github.com/jrburke/r.js/blob/master/build/example.build.js#L438 )
As to your specific problem: your lazy require(['dropdown']) call is misleading you. By combining the requested module id with the basePath, RequireJS comes up with the URL you want - scripts/modules/dropdown - which defines a module with the module id scripts/module/dropdown - but since you requested the module id dropdown, you get nothing. (I would've guessed you'd get a RuntimeError instead of undefined, but I suppose that's how things go). One way or another you need to address the id/path mismatches.
Although I have resolved my issue with the hints wyantb's answer provided, I've since changed my approach to a single file concat due to the simplicity it brings. I still wanted to post the specifics of how I solved this question's issue for anyone else to happens along it.
In the grunt build configuration options, I added the onBuildWrite field to transform the content, so my assigned module IDs lined up with how I was lazily loading them.
onBuildWrite: function (moduleName, path, contents) {
return contents.replace(/modules\/global.js/, 'global');
}
This code is specifically for the global.js file. I implemented a similar onBuildWrite for the other module files (in the foreach loop). The transformation will essentially strip the path and extension from the module name that r.js assigns.
Here are some examples of before and after:
Before After
/modules/global.js global
/modules/dropdown/dropdown.js dropdown
/modules/loginButton/loginButton.js loginButton
Therefore, when I load the modules using the HTML script from my original question, requirejs resolves and finds a match.
Either require by path or define global and dropdown in global.cs
require(['./global'], function () {
require(['./dropdown'], function (dropdown) {
console.log(dropdown);
});
});
I have an application which has an app object which does the start routine and stores useful things like app.state and app.user. However I am trying to access this app instance without passing this from the app instance all the way around my large codebase.
Strangely I work on other projects which include app in the same way as in something.js and it works but I can't see why.
index.html
<!DOCTYPE html>
<html>
<head>
<title>Cannot require app in another file</title>
</head>
<body>
<script data-main="config" src="require.js"></script>
</body>
</html>
config.js
requirejs.config({
deps: ['app']
});
app.js
define([
'something'
], function(Something) {
'use strict';
var App = function() {
this.name = 'My app';
};
return new App();
});
something.js
define([
'require',
'app'
], function (require, app) {
'use strict';
var SomeModule = function() {
app = require('app'); // EXCEPTION
console.log('App:', app);
};
return new SomeModule();
});
When loading this requirejs exception is throw because of the require in SomeModule:
Uncaught Error: Module name "app" has not been loaded yet for context: _
Demo of above (see console for error): http://dominictobias.com/circulardep/
It's not clear to me why you need to have a circular dependency. As stated in the documentation for RequireJS:
Circular dependencies are rare, and usually a sign that you might want to rethink the design.
This being said, if you do need the circular dependency, the issue with your code is that require('app') is called too early. It cannot be called until after the module something has returned its value. Right now, it is called before the value is returned. If you look at the code given as example in the documentation:
define(["require", "a"],
function(require, a) {
//"a" in this case will be null if a also asked for b,
//a circular dependency.
return function(title) {
return require("a").doSomething();
}
}
);
you see that the module returns a function which then would be called by the code that required the module, which happens after this module has returned its value.
So how do you fix this? What you could do is have the class you return call a function that fetches module app whenever needed. So:
define([
'require',
'app'
], function (require) {
'use strict';
var app_;
function fetch_app() {
if (app_ === undefined)
app_ = require("app");
return app_;
}
var SomeModule = function() {
// ...
};
SomeModule.prototype.doSomethingWithApp = function () {
var app = get_app();
app.whatever();
};
return new SomeModule();
});
I've removed app from the list of arguments and store the value of the app module in app_ because doing it this way provides for early detection of a missing call to get_app() in any method of SomeModule. If app is made a parameter of the module's factory function then using app inside a method without calling get_app() first would be detected only if it so happened that no other method that calls get_app() was called first. (Of course, I could type app_ and face the same problem as the one I aim to prevent. It's a matter of respective likelihoods: I'd be very likely to forget to call get_app() everywhere it is needed because I don't usually write code with circular dependencies. However, I'd be unlikely to type app_ for app because I don't usually put _ at the end of my variable names.)
I am new to nodejs and browserify. I started with this link .
I have file main.js which contains this code
var unique = require('uniq');
var data = [1, 2, 2, 3, 4, 5, 5, 5, 6];
this.LogData =function(){
console.log(unique(data));
};
Now I Install the uniq module with npm:
npm install uniq
Then I bundle up all the required modules starting at main.js into a single file called bundle.js with the browserify command:
browserify main.js -o bundle.js
The generated file looks like this:
(function e(t,n,r){function s(o,u){if(!n[o]){if(!t[o]){var a=typeof require=="function"&&require;if(!u&&a)return a(o,!0);if(i)return i(o,!0);throw new Error("Cannot find module '"+o+"'")}var f=n[o]={exports:{}};t[o][0].call(f.exports,function(e){var n=t[o][1][e];return s(n?n:e)},f,f.exports,e,t,n,r)}return n[o].exports}var i=typeof require=="function"&&require;for(var o=0;o<r.length;o++)s(r[o]);return s})({1:[function(require,module,exports){
var unique = require('uniq');
var data = [1, 2, 2, 3, 4, 5, 5, 5, 6];
this.LogData =function(){
console.log(unique(data));
};
},{"uniq":2}],2:[function(require,module,exports){
"use strict"
function unique_pred(list, compare) {
var ptr = 1
, len = list.length
, a=list[0], b=list[0]
for(var i=1; i<len; ++i) {
b = a
a = list[i]
if(compare(a, b)) {
if(i === ptr) {
ptr++
continue
}
list[ptr++] = a
}
}
list.length = ptr
return list
}
function unique_eq(list) {
var ptr = 1
, len = list.length
, a=list[0], b = list[0]
for(var i=1; i<len; ++i, b=a) {
b = a
a = list[i]
if(a !== b) {
if(i === ptr) {
ptr++
continue
}
list[ptr++] = a
}
}
list.length = ptr
return list
}
function unique(list, compare, sorted) {
if(list.length === 0) {
return []
}
if(compare) {
if(!sorted) {
list.sort(compare)
}
return unique_pred(list, compare)
}
if(!sorted) {
list.sort()
}
return unique_eq(list)
}
module.exports = unique
},{}]},{},[1])
After including bundle.js file into my index.htm page, how do I call logData function ??
The key part of bundling standalone modules with Browserify is the --s option. It exposes whatever you export from your module using node's module.exports as a global variable. The file can then be included in a <script> tag.
You only need to do this if for some reason you need that global variable to be exposed. In my case the client needed a standalone module that could be included in web pages without them needing to worry about this Browserify business.
Here's an example where we use the --s option with an argument of module:
browserify index.js --s module > dist/module.js
This will expose our module as a global variable named module.
Source.
Update:
Thanks to #fotinakis. Make sure you're passing --standalone your-module-name. If you forget that --standalone takes an argument, Browserify might silently generate an empty module since it couldn't find it.
Hope this saves you some time.
By default, browserify doesn't let you access the modules from outside of the browserified code – if you want to call code in a browserified module, you're supposed to browserify your code together with the module. See http://browserify.org/ for examples of that.
Of course, you could also explicitly make your method accessible from outside like this:
window.LogData =function(){
console.log(unique(data));
};
Then you could call LogData() from anywhere else on the page.
#Matas Vaitkevicius's answer with Browserify's standalone option is correct (#thejh's answer using the window global variable also works, but as others have noted, it pollutes the global namespace so it's not ideal). I wanted to add a little more detail on how to use the standalone option.
In the source script that you want to bundle, make sure to expose the functions you want to call via module.exports. In the client script, you can call these exposed functions via <bundle-name>.<func-name>. Here's an example:
My source file src/script.js will have this:
module.exports = {myFunc: func};
My browserify command will look something like this:
browserify src/script.js --standalone myBundle > dist/bundle.js
And my client script dist/client.js will load the bundled script
<script src="bundle.js"></script>
and then call the exposed function like this:
<script>myBundle.myFunc();</script>
There's no need to require the bundle name in the client script before calling the exposed functions, e.g. <script src="bundle.js"></script><script>var bundled = require("myBundle"); bundled.myFunc();</script> isn't necessary and won't work.
In fact, just like all functions bundled by browserify without standalone mode, the require function won't be available outside of the bundled script. Browserify allows you to use some Node functions client-side, but only in the bundled script itself; it's not meant to create a standalone module you can import and use anywhere client-side, which is why we have to go to all this extra trouble just to call a single function outside of its bundled context.
I just read through the answers and seems like nobody mentioned the use of the global variable scope? Which is usefull if you want to use the same code in node.js and in the browser.
class Test
{
constructor()
{
}
}
global.TestClass = Test;
Then you can access the TestClass anywhere.
<script src="bundle.js"></script>
<script>
var test = new TestClass(); // Enjoy!
</script>
Note: The TestClass then becomes available everywhere. Which is the same as using the window variable.
Additionally you can create a decorator that exposes a class to the global scope. Which is really nice but makes it hard to track where a variable is defined.
Read README.md of browserify about --standalone parameter
or google "browserify umd"
Minimal runnable example
This is basically the same as: https://stackoverflow.com/a/43215928/895245 but with concrete files that will allow you to just run and easily reproduce it yourself.
This code is also available at: https://github.com/cirosantilli/browserify-hello-world
index.js
const uniq = require('uniq');
function myfunc() {
return uniq([1, 2, 2, 3]).join(' ');
}
exports.myfunc = myfunc;
index.html
<!doctype html>
<html lang=en>
<head>
<meta charset=utf-8>
<title>Browserify hello world</title>
</head>
<body>
<div id="container">
</body>
</div>
<script src="out.js"></script>
<script>
document.getElementById('container').innerHTML = browserify_hello_world.myfunc();
</script>
</html>
Node.js usage:
#!/usr/bin/env node
const browserify_hello_world = require('./index.js');
console.log(browserify_hello_world.myfunc());
Generate out.js for browser usage:
npx browserify --outfile out.js --standalone browserify_hello_world index.js
Both the browser and the command line show the expected output:
1 2 3
Tested with Browserify 16.5.0, Node.js v10.15.1, Chromium 78, Ubuntu 19.10.
To have your function available from both the HTML and from server-side node:
main.js:
var unique = require('uniq');
function myFunction() {
var data = [1, 2, 2, 4, 3];
return unique(data).toString();
}
console.log ( myFunction() );
// When browserified - we can't call myFunction() from the HTML, so we'll externalize myExtFunction()
// On the server-side "window" is undef. so we hide it.
if (typeof window !== 'undefined') {
window.myExtFunction = function() {
return myFunction();
}
}
main.html:
<html>
<head>
<script type='text/javascript' src="bundle.js"></script>
<head>
<body>
Result: <span id="demo"></span>
<script>document.getElementById("demo").innerHTML = myExtFunction();</script>
</body>
</html>
Run:
npm install uniq
browserify main.js > bundle.js
and you should get same results when opening main.html in a browser as when running
node main.js
Whole concept is about wrapping.
1.) Alternative - Object "this"
for this purpose I'll assume you have "only 1 script for whole app {{app_name}}" and "1 function {{function_name}}"
add function {{function_name}}
function {{function_name}}(param) { ... }
to object this
this.{{function_name}} = function(param) { ... }
then you have to name that object to be available - you will do it add param "standalone with name" like others advised
so if you use "watchify" with "browserify" use this
var b = browserify({
...
standalone: '{{app_name}}'
});
or command line
browserify index.js --standalone {{app_name}} > index-bundle.js
then you can call the function directly
{{app_name}}.{{function_name}}(param);
window.{{app_name}}.{{function_name}}(param);
2.) Alternative - Object "window"
add function {{function_name}}
function {{function_name}}(param) { ... }
to object window
window.{{function_name}} = function(param) { ... }
then you can call the function directly
{{function_name}}(param);
window.{{function_name}}(param);
You have a few options:
Let plugin browserify-bridge auto-export the modules to a generated entry module. This is helpful for SDK projects or situations where you don't have to manually keep up with what is exported.
Follow a pseudo-namespace pattern for roll-up exposure:
First, arrange your library like this, taking advantage of index look-ups on folders:
/src
--entry.js
--/helpers
--- index.js
--- someHelper.js
--/providers
--- index.js
--- someProvider.js
...
With this pattern, you define entry like this:
exports.Helpers = require('./helpers');
exports.Providers = require('./providers');
...
Notice the require automatically loads the index.js from each respective sub-folder
In your subfolders, you can just include a similar manifest of the available modules in that context:
exports.SomeHelper = require('./someHelper');
This pattern scales really well and allows for contextual (folder by folder) tracking of what to include in the rolled-up api.
You can also call your function from the html file like this:
main.js: (will be in bundle.js)
window.onload = function () {
document.getElementById('build-file')
.addEventListener('click', buildFile)
}
function buildFile() {
...
}
index.html:
<button id="build-file"">Build file</button>
window.LogData =function(data){
return unique(data);
};
Call the function simply by LogData(data)
This is just a slight modification to thejh's answer but important one
For debugging purposes I added this line to my code.js:
window.e = function(data) {eval(data);};
Then I could run anything even outside the bundle.
e("anything();");