Installing TypeScript requires node.js. And I assume that TypeScript uses Node.js to compile the .ts to a .js file.
My question is, does that created .js file require node.js? The ones I've seen so far appear not to. I don't want to load node.js into my html pages if it's not used.
thanks - dave
No, TypeScript just emits regular JavaScript.
If you use the "external modules" feature of the language (import x = require('foo');) you'll need to compile for either CommonJS (node) or AMD (require.js) and have those available, but that's opt-in.
Related
I have started working on an existing project based on Node.js. I was just trying to understand the flow of execution, where I encountered with some *.mjs files. I have searched the web where I found that these are module based JS-files.
I want to know how is it different from *.js files (how does it benefit)?
It indicates an ES6 module file.
Node.js's original module system is CommonJs (which uses require and module.exports).
Since Node.js was created, the ECMAScript module system (which uses import and export) has become standard and Node.js has added support for it.
Node.js will treat .cjs files as CommonJS modules and .mjs files as ECMAScript modules. It will treat .js files as whatever the default module system for the project is (which is CommonJS unless package.json says "type": "module",).
See also: Differences between ES6 module system and CommonJs
.MJS file
mjs an extension for EcmaScript modules
An MJS file is a source code file containing an ES Module (ECMAScript Module) for use with a Node.js application.
MJS files are written in JavaScript, and may also use the .JS extension outside of the Node.js context.
ES Modules allow web and application developers to organize code into smaller reusable components.
ECMAScript 6 (ES6) introduced the specification for ES Modules, providing a standard for implementing modules in JavaScript. As of 2018, all major web browsers support ES Modules.
However, the popularity of modularized JavaScript pre-dates ES6. Node.js, a JavaScript runtime environment, used CommonJS as the specification for modules. Because so many existing applications were built with CommonJS, when Node.js added support for native ES modules, it controversially introduced the MJS file extension to differentiate the two and prevent applications from breaking.
NOTE: Some developers informally refer to MJS files as "Michael Jackson Script" files.
For clarity. As for devs/humans, it's easy to distinguish between a module file(.mjs) and a normal javascript file(.js)... because it's not always easy to determine even if you examine the code in the file.
There are also performance benefits which gives you more reason to consider using it.
V8(JavaScript engine that powers Google Chrome) recommends the use of .mjs but it still depends on your situation. If you want to know more of it's advantages, check https://v8.dev/features/modules#mjs
I was learning babel and webpack and then it turns out I need to install node.js to run them both and I asked myself WHY? Then according to my research, we need node.js for webpack and babel since both of them were written in JS and to run that JS code which transpiles( for babel) and bundles up the code(for webpack). Also, another reason is that since both babel and webpack handles our JS code outside of the browser, this is the reason to use Node.js. Are these reasons true?
According to the Node.js website -
Node.js® is a JavaScript runtime built on Chrome's V8 JavaScript engine.
Webpack and babel (along with many other tools you might use for frontend development) are written in javascript and since they are command line tools, they need a way to run outside of the browser (directly on your machine).
They could have used some other language to write the tools but since they chose to write them in javascript, Node.js is the only feasible options right now.
In case you are interested, the original creator of nodejs
Ryan Dahl has built another secure runtime environment for Javascript/Typescript called Deno
Yes, at the moment the node.js project is non-portable by full open source disclosure nor extension to port node.js commonjs without a just in time transpiler with a service worker on a server.
Definitions: FHC = "from half court"
Babel and webpack
(1) transpile/move (write&read, not ln -s sym...bolic link) & (2) compost/pile onto a JIT target,
like v8 or other browser-javascript-interpreters. v8 on a service worker can compile on the edge just in time for interpretation in a browser v8 environment but still on the cloudflare edge server.
Declare (FHC) Allegedly, rust provides webassembly modules with the lipid [llvm-]wrappings
that nucleic acid exocytosis needs to be a full-blown virus, err I mean
Initiation Routine needs to be a targetable JIT extension!
A compiler/transpiler still requires it's target-scope receivable. Declare (FHC) Emit is to execute as compile is to interpret, even AST.
I'm learning how to use Flux and I encountered the following line in the documentation: "We can use Node's EventEmitter to get started with a store."
I understand that you can use things like Browserify to do the bundling and minifying, grabbing all the dependencies that Node code has to make the bundled browser-compatible JS file. But what's bugging me right now is how you know what you can do this with. How do we know what Node code we're allowed to use in the browser?
So, first of all let's consider that when in node you have
JavaScript modules that are the 3rdParty modules written in JavaScript (ECMA5, ECMA6 and even TypeScript or CoffeScript) etc;
Node built-in module. Those are node Core modules like fs, path, util, etc.
native compiled module called Addons that are are
dynamically-linked shared objects, written in C or C++;
Then you have the packager / module bundlers
Browserify
Webpack
the transpilers i.e. source to source compilers that typicall will handle syntax tranforms like
Babel.js that shims modern JavaScript to legacy engines
and the techniques
ECMA5 Shim to support legacy JavaScript engines
HTML5 Cross-Browser Polyfills
Because you need to do polyfills if you want to transform not only syntax but even globals (like the Promise), so you combine transpiler to polyfill having like babel-polyfill
Finally we have different kind of modules design patterns (modules format) to be handled for the bundling process:
AMD modules format
CommonJS modules format
and formats that are not in those ones that must be bundled/shimmed - where possible - through custom loaders.
That said, native modules will not run in the browser: you cannot bundle a native module through Webpack. Ordinary modules will, but not all. This is due to several reasons. There are some specific methods that cannot be "browserified" or "webpacked". Let's take as example fs. Can you put this built-in module in the browser? There are some abstraction for that called brfs, that are transforms for built-in node apis fs.readFileSync() and fs.readFile(), so you will do
$ browserify -t brfs example/main.js > bundle.js
to get
var fs = require('fs');
var html = fs.readFileSync(__dirname + '/robot.html', 'utf8');
console.log(html);
This will not work for every non built-in modules, in the npm modules jungle, so WebPack has a module.noParse option to exclude Addons modules, non supported modules, etc. - see here about that.
So you have to look at the list of the transforms that means you can apply this transform to browserify to obtain like the fs transform mentioned above.
So that said, how do you know that a certain module will run in the browser? When you design your web application and Node backend you have to do opportunistic design choises to design shared modules/library that will run in both the environment, so being shimmed/packed at some point, like object models, application logic, etc., other modules that will deal with the File System I/O or will use native addons, so that will work in the server only, packing through wrappers it's possibile, but the behavior will look differently, as we have seen in the fs example above, and web specific modules, so it's a design matter.
A note can be added about networking modules i.e. node http, https that thanks to library abstractions like node request will run everywhere or using specific transforms like http-browserify.
I setup a website with regular client side RequireJS today. Than I did some research on node, got that installed and setup my first module in node. When I setup the first require, I loaded the Require.JS file and I get all that. The thing that is confusing me is, I created a file called test.js and within that I am including:
var require = require("requirejs");
which is actually including the node require, not the original require library I was using right?
So like are they completely different? Can they used together?
Doesn't Node already have a module loader?
Yes Node does.
That loader uses the CommonJS module format. The
CommonJS module format is non-optimal for the browser, and I do not
agree with some of the trade-offs made in the CommonJS module format.
By using RequireJS on the server, you can use one format for all your
modules, whether they are running server side or in the browser. That
way you can preserve the speed benefits and easy debugging you get
with RequireJS in the browser, and not have to worry about extra
translation costs for moving between two formats. If you want to use
define() for your modules but still run them in Node without needing
to run RequireJS on the server, see the section below about using
amdefine.
Source: http://requirejs.org/docs/node.html#1
Ok, so modules written for node.js can be combined into bundles with browserify.
But just in case I only have a bunch of bundles created by browserify and not the source, would it still be possible to 'require' or otherwise use these bundles and their contents in a node.js environment besides the browser? (granted that the code does not do anything browser specific)
Ok, so modules written for node.js can be combined into bundles with
browserify.
Firstly I am not sure what you mean by this, as browserify was created to do the opposite. Browserify was made to allow the use of node's require() statements in the browser.
But just in case I only have a bunch of bundles created by browserify
and not the source, would it still be possible to 'require' or
otherwise use these bundles and their contents in a node.js
environment besides the browser? (granted that the code does not do
anything browser specific)
Yes in short, as long as the modules do not use the global window scope because window is undefined in node.js. Common helper packages like lodash, axios, moment, bluebird, and q promises all work in node.js.
Generally though, packages are often modified to work in both the browser and node.js. There is a browser attribute option in package.json files that allows you to specifically target the browser when publishing npm modules. Often files designed for the browser are minified down to one file because of how files could potentially be imported into the browser. This is not necessary with node and there may be many files in a node project.