I maintain a package called react-querybuilder that generates unique identifiers using crypto.getRandomValues().
When used in the browser, this is not a problem as crypto is available pretty much everywhere now. But react-querybuilder can be used on the server for query processing (including generating IDs) as well as server-side rendering, which means the crypto package must either be polyfilled with crypto-browserify or loaded manually (something like globalThis.crypto = require('node:crypto')).
Some build setups require the polyfill even if they don't do SSR, e.g. Create React App v5 since it uses Webpack v5 (which doesn't automatically include polyfills like v4 did). CRA v4 doesn't have the issue.
How can I write the package to use window.crypto when running in the browser, but load node:crypto and use that instead when running on the server? Ideally the setup would avoid requiring anything extra of the end user (polyfills, config, etc.).
This is the current implementation at time of writing (comments removed):
let cryptoModule = globalThis.crypto;
if (!cryptoModule && typeof require === "function") {
cryptoModule = require("crypto").webcrypto;
}
const template = "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx";
const position19vals = ["8", "9", "a", "b"];
const re = /[xy]/g;
const container = new Uint32Array(32);
export const generateID = () => {
cryptoModule.getRandomValues(container);
let i = -1;
return template.replaceAll(re, (char) => {
i++;
return char === "y"
? position19vals[container[i] % 4]
: (container[i] % 16).toString(16);
});
};
FWIW, I'm not opposed to having separate builds for client and server if that makes it easier to implement (for me and the end user, but mostly the end user).
Related
I understand eval string-to-function is impossible to use on the browsers' application programming interfaces, but there must be another strategy to use third party dependencies without node.js on v8 engine, given Cloudflare does it in-house, unless they disable the exclusive method by necessity or otherwise on their edge servers for Workers. I imagine I could gather the AST of the commonjs module, as I was able to by rollup watch, but what might the actual steps be, by tooling? I mention AMD for it seems to rely on string-to-function (to-which I've notice Mozilla MDN says nothing much about it).
I have been exploring the require.js repositories, and they either use eval or AST
function DEFNODE(type, props, methods, base) {
if (arguments.length < 4) base = AST_Node;
if (!props) props = [];
else props = props.split(/\s+/);
var self_props = props;
if (base && base.PROPS) props = props.concat(base.PROPS);
var code = "return function AST_" + type + "(props){ if (props) { ";
for (var i = props.length; --i >= 0; ) {
code += "this." + props[i] + " = props." + props[i] + ";";
}
var proto = base && new base();
if ((proto && proto.initialize) || (methods && methods.initialize))
code += "this.initialize();";
code += "}}";
//constructor
var cnstor = new Function(code)();
if (proto) {
cnstor.prototype = proto;
cnstor.BASE = base;
}
if (base) base.SUBCLASSES.push(cnstor);
cnstor.prototype.CTOR = cnstor;
cnstor.PROPS = props || null;
cnstor.SELF_PROPS = self_props;
cnstor.SUBCLASSES = [];
if (type) {
cnstor.prototype.TYPE = cnstor.TYPE = type;
}
if (methods)
for (i in methods)
if (HOP(methods, i)) {
if (/^\$/.test(i)) {
cnstor[i.substr(1)] = methods[i];
} else {
cnstor.prototype[i] = methods[i];
}
}
//a function that returns an object with [name]:method
cnstor.DEFMETHOD = function (name, method) {
this.prototype[name] = method;
};
if (typeof exports !== "undefined") exports[`AST_${type}`] = cnstor;
return cnstor;
}
var AST_Token = DEFNODE(
"Token",
"type value line col pos endline endcol endpos nlb comments_before file raw",
{},
null
);
https://codesandbox.io/s/infallible-darwin-8jcl2k?file=/src/mastercard-backbank/uglify/index.js
https://www.youtube.com/watch?v=EF7UW9HxOe4
Is it possible to make a C++ addon just to add a default object for
node.js named exports or am I Y’ing up the wrong X
'.so' shared library for C++ dlopen/LoadLibrary (or #include?)
“I have to say that I'm amazed that there is code out there that loads one native addon from another native addon! Is it done by acquiring and then calling an instance of the require() function, or perhaps by using uv_dlopen() directly?”
N-API: An api for embedding Node in applications
"[there is no ]napi_env[ just yet]."
node-api: allow retrieval of add-on file name - Missing module in Init
Andreas Rossberg - is AST parsing, or initialize node.js abstraction for native c++, enough?
v8::String::NewFromUtf8(isolate, "Index from C++!");
Rising Stack - Node Source
"a macro implicit" parameter - bridge object between
C++ and JavaScript runtimes
extract a function's parameters and set the return value.
#include <nan.h>
int build () {
NAN_METHOD(Index) {
info.GetReturnValue().Set(
Nan::New("Index from C++!").ToLocalChecked()
);
}
}
// Module initialization logic
NAN_MODULE_INIT(Initialize) {
/*Export the `Index` function
(equivalent to `export function Index (...)` in JS)*/
NAN_EXPORT(target, Index);
}
New module "App" Initialize function from NAN_MODULE_INIT (an atomic?-macro)
"__napi_something doesn't exist."
"node-addon-API module for C++ code (N-API's C code's headers)"
NODE_MODULE(App, Initialize);
Sep 17, 2013, 4:42:17 AM to v8-u...#googlegroups.com "This comes up
frequently, but the answer remains the same: scrap the idea. ;)
Neither the V8 parser nor its AST are designed for external
interfacing. In particular (1) V8's AST does not necessarily reflect
JavaScript syntax 1-to-1, (2) we change it all the time, and (3) it
depends on various V8 internals. And since all these points are
important for V8, don't expect the situation to change.
/Andreas"
V8 c++: How to import module via code to script context (5/28/22, edit)
"The export keyword may only be used in a module interface unit.
The keyword is attached to a declaration of an entity, and causes that
declaration (and sometimes the definition) to become visible to module
importers[ - except for] the export keyword in the module-declaration, which is just a re-use of the keyword (and does not actually “export” ...entities)."
SyntheticModule::virtual
ScriptCompiler::CompileModule() - "Corresponds to the ParseModule abstract operation in the ECMAScript specification."
Local<Function> foo_func = ...;//external
Local<Module> module = Module::CreateSyntheticModule(
isolate, name,
{String::NewFromUtf8(isolate, "foo")},
[](Local<Context> context, Local<Module> module) {
module->SetSyntheticModuleExport(
String::NewFromUtf8(isolate, "foo"), foo_func
);
});
Context-Aware addons from node.js' commonjs modules
export module index;
export class Index {
public:
const char* app() {
return "done!";
}
};
import index;
import <iostream>;
int main() {
std::cout << Index().app() << '\n';
}
node-addon-api (new)
native abstractions (old)
"Thanks to the crazy changes in V8 (and some in Node core), keeping native addons compiling happily across versions, particularly 0.10 to 0.12 to 4.0, is a minor nightmare. The goal of this project is to store all logic necessary to develop native Node.js addons without having to inspect NODE_MODULE_VERSION and get yourself into a macro-tangle[ macro = extern atomics?]."
Scope Isolate (v8::Isolate), variable Local (v8::Local)
typed_array_to_native.cc
"require is part of the Asynchronous Module Definition AMD API[, without "string-to-function" eval/new Function()],"
node.js makes objects, for it is written in C++.
"According to the algorithm, before finding
./node_modules/_/index.js, it tried looking for express in the
core Node.js modules. This didn’t exist, so it looked in node_modules,
and found a directory called _. (If there was a
./node_modules/_.js, it would load that directly.) It then
loaded ./node_modules/_/package.json, and looked for an exports
field, but this didn’t exist. It also looked for a main field, but
this didn’t exist either. It then fell back to index.js, which it
found. ...require() looks for node_modules in all of the parent directories of the caller."
But java?
I won't accept this answer until it works, but this looks promising:
https://developer.oracle.com/databases/nashorn-javascript-part1.html
If not to run a jar file or something, in the Worker:
https://github.com/nodyn/jvm-npm
require and build equivalent in maven, first, use "dist/index.js".
Specifically: [ScriptEngineManager][21]
https://stackoverflow.com/a/15787930/11711280
Actually: js.commonjs-require experimental
https://docs.oracle.com/en/graalvm/enterprise/21/docs/reference-manual/js/Modules/
Alternatively/favorably: commonjs builder in C (v8 and node.js)
https://www.reddit.com/r/java/comments/u7elf4/what_are_your_thoughts_on_java_isolates_on_graalvm/
Here I will explore v8/node.js src .h and .cc for this purpose
https://codesandbox.io/s/infallible-darwin-8jcl2k?file=/src/c.cpp
I'm curious why there is near machine-level C operability in Workers if not to use std::ifstream, and/or build-locally, without node.js require.
Can node's module loader support TS's baseUrl compiler option?
TS 2 introduced the baseUrl compiler option, to effectively enable project relative require() and import requests.
However, this requires the module loader to support the same thing, as TS doesn't actually rewrite the request during transpilation. For tools like webpack, this is fairly straightforward.
Unfortunately, when using TS to develop node applications (.i.e backend services, command line tools, electron desktop apps) there didn't seem to be a way to change node's module loader behavior.
Is there a way?
Yes!
Appreciating TS's position, here's a simple solution to the 90% use case for those of us using node, but wanting the convenience of using baseUrl relative require() calls without any fuss.
This solution hooks node's require() call, and resolves requests using the dirname of "main" to mimic baseUrl. It therefore assumes the baseUrl compiler option was also set to the same directory where the source "main.ts" was located.
To use, paste this tiny chunk of code at the top of your "main.ts".
import * as path from 'path'
import * as fs from 'fs'
(function() {
const CH_PERIOD = 46
const baseUrl = path.dirname(process['mainModule'].filename)
const existsCache = {d:0}; delete existsCache.d
const moduleProto = Object.getPrototypeOf(module)
const origRequire = moduleProto.require
moduleProto.require = function(request) {
let existsPath = existsCache[request]
if(existsPath === undefined) {
existsPath = ''
if(!path.isAbsolute(request) && request.charCodeAt(0) !== CH_PERIOD) {
const ext = path.extname(request)
const basedRequest = path.join(baseUrl, ext ? request : request + '.js')
if(fs.existsSync(basedRequest)) existsPath = basedRequest
else {
const basedIndexRequest = path.join(baseUrl, request, 'index.js')
existsPath = fs.existsSync(basedIndexRequest) ? basedIndexRequest : ''
}
}
existsCache[request] = existsPath
}
return origRequire.call(this, existsPath || request)
}
})()
I'm working on some repo. And add refactoring to extract some functionality into class
The question is -- I prefer to use passing dependencies from outside (DI). But I see that it's not common pattern for node.js application.
So the question - is there any good examples ( links to repos ) where guys use DI for providing dependencies.
The opposite opinion is -- "We always can use proxyquire module to mock dependencies"
P.S
example for code I propose is
// use
const inst = new Cls(getDep1(), getDep2());
// where getDep1 / getDep2 provide dependencies from side modules
instead of
//Cls
const dep1 = require('dep1');
const dep2 = require('dep2');
module.exports = function Cls() {
// deps usage
}
// and
const inst = new Cls();
The question is about arguments in node.js related projects
Your example is about as clear as it gets. If you want to configure a stub/mock in a test for a class dependency without using proxyquire or mockery or some other require patcher, then you have to provide another point of entry into your code.
you could explicitly use DI like in your example:
function Cls(dep1, dep2) {
this.dep1 = dep1;
this.dep2 = dep2;
}
Which could live off by itself, then your calling code would be responsible for importing your class, configuring its dependencies, and instantiating it correctly. That way your Cls is isolated and unit testable itself.
You could also expose the dependencies that need to be handled as public properties:
const dep1 = require('dep1');
const dep2 = require('dep2');
module.exports = function Cls() {
this.dep1 = dep1;
this.dep2 = dep2;
}
That could allow the module that Cls is defined in to also contain the code that associates it with its deps, while still allowing your unit tests to easily configure Cls with mock/stub objects. This relies on requires to be side effect free :(
var cls = new Cls();
cls.dep1 = new SomeStub();
cls.dep2 = new SomeStub();
cls.exercise();
A new instance of third-party module should be required in one of the modules.
// a
...
exports.thirdParty = require('third-party');
// b
...
exports.thirdParty = require('third-party');
// first-party
...
exports.thirdParty = requireFreshInstance('third-party');
// app.js
var assert = require('assert');
var a = require('a');
var firstParty = require('first-party');
var b = require('b');
assert(a.thirdParty === b.thirdParty);
assert(firstParty.thirdParty !== a.thirdParty);
assert(firstParty.thirdParty !== b.thirdParty);
All of the listed modules have similar package requirements,
dependencies: {
"third-party": "^1"
}
And the requirement is that it should stay intact, no tricks like "third-party": "git://..." are allowed.
Let's say the user controls only first-party module and can't modify third-party module to have a new factory method that would return a new instance.
I'm aware of the fact that third-party is cached once if the version is the same in all cases (technically it is full path to third-party that matters), most likely .thirdParty properties in all objects are equal.
How can this problem be solved in Node.js programmatically (not with package.json)?
Here is one module require-new could meet your requirement.
require-new requires a new module object.
require-new does not affect the state or behavior of require
method.
require-new has been designed to be used for module testing.
Here are sample from this module.
require('./rand.js'); // 0.697190385311842
require('./rand.js'); // 0.697190385311842
Modules are cached in a require.cache object when they are required.
require-new deletes the key value from the require.cache object associated with the module you are requesting, making the module reload:
requireNew('./rand.js'); // 0.2123227424453944
requireNew('./rand.js'); // 0.5403654584661126
How can I detect whether my Node.JS file was called using SH:node path-to-file or JS:require('path-to-file')?
This is the Node.JS equivalent to my previous question in Perl: How can I run my Perl script only if it wasn't loaded with require?
if (require.main === module) {
console.log('called directly');
} else {
console.log('required as a module');
}
See documentation for this here: https://nodejs.org/docs/latest/api/modules.html#modules_accessing_the_main_module
There is another, slightly shorter way (not outlined in the mentioned docs).
var runningAsScript = !module.parent;
I outlined more details about how this all works under the hood in this blog post.
For those using ES Modules (and Node 10.12+), you can use import.meta.url:
import path from 'path';
import { fileURLToPath } from 'url'
const nodePath = path.resolve(process.argv[1]);
const modulePath = path.resolve(fileURLToPath(import.meta.url))
const isRunningDirectlyViaCLI = nodePath === modulePath
Things like require.main, module.parent and __dirname/__filename aren’t available in ESM.
Note: If using ESLint it may choke on this syntax, in which case you’ll need to update to ESLint ^7.2.0 and turn your ecmaVersion up to 11 (2020).
More info: process.argv, import.meta.url
I was a little confused by the terminology used in the explanation(s). So I had to do a couple quick tests.
I found that these produce the same results:
var isCLI = !module.parent;
var isCLI = require.main === module;
And for the other confused people (and to answer the question directly):
var isCLI = require.main === module;
var wasRequired = !isCLI;
Try this if you are using ES6 modules:
if (process.mainModule.filename === __filename) {
console.log('running as main module')
}
I always find myself trying to recall how to write this goddamn code snippet, so I decided to create a simple module for it. It took me a bit to make it work since accessing caller's module info is not straightforward, but it was fun to see how it could be done.
So the idea is to call a module and ask it if the caller module is the main one. We have to figure out the module of the caller function. My first approach was a variation of the accepted answer:
module.exports = function () {
return require.main === module.parent;
};
But that is not guaranteed to work. module.parent points to the module which loaded us into memory, not the one calling us. If it is the caller module that loaded this helper module into memory, we're good. But if it isn't, it won't work. So we need to try something else. My solution was to generate a stack trace and get the caller's module name from there:
module.exports = function () {
// generate a stack trace
const stack = (new Error()).stack;
// the third line refers to our caller
const stackLine = stack.split("\n")[2];
// extract the module name from that line
const callerModuleName = /\((.*):\d+:\d+\)$/.exec(stackLine)[1];
return require.main.filename === callerModuleName;
};
Save this as is-main-module.js and now you can do:
const isMainModule = require("./is-main-module");
if (isMainModule()) {
console.info("called directly");
} else {
console.info("required as a module");
}
Which is easier to remember.
First, let's define the problem better. My assumption is that what you are really looking for is whether your script owns process.argv (i.e. whether your script is responsible for processing process.argv). With this assumption in mind, the code and tests below are accurate.
module.parent works excellently, but it is deprecated for good reasons (a module might have multiple parents, in which case module.parent only represents the first parent), so use the following future-proof condition to cover all cases:
if (
typeof process === 'object' && process && process.argv
&& (
(
typeof module === 'object' && module
&& (
!module.parent
|| require.main === module
|| (process.mainModule && process.mainModule.filename === __filename)
|| (__filename === "[stdin]" && __dirname === ".")
)
)
|| (
typeof document === "object"
&& (function() {
var scripts = document.getElementsByTagName("script");
try { // in case we are in a special environment without path
var normalize = require("path").normalize;
for (var i=0,len=scripts.length|0; i < len; i=i+1|0)
if (normalize(scripts[i].src.replace(/^file:/i,"")) === __filename)
return true;
} catch(e) {}
})()
)
)
) {
// this module is top-level and invoked directly by the CLI
console.log("Invoked from CLI");
} else {
console.log("Not invoked from CLI");
}
It works correctly in all of the scripts in all of the following cases and never throws any errors†:
Requiring the script (e.x. require('./main.js'))
Directly invoking the script (e.x. nodejs cli.js)
Preloading another script (e.x. nodejs -r main.js cli.js)
Piping into node CLI (e.x. cat cli.js | nodejs)
Piping with preloading (e.x. cat cli.js | nodejs -r main.js)
In workers (e.x. new Worker('./worker.js'))
In evaled workers (e.x. new Worker('if (<test for CLI>) ...', {eval: true}))
Inside ES6 modules (e.x. nodejs --experimental-modules cli-es6.js)
Modules with preload (e.x. nodejs --experimental-modules -r main-es6.js cli-es6.js)
Piped ES6 modules (e.x. cat cli-es6.js | nodejs --experimental-modules)
Pipe+preload module (e.x. cat cli-es6.js | nodejs --experimental-modules -r main-es6.js)
In the browser (in which case, CLI is false because there is no process.argv)
In mixed browser+server environments (e.x. ElectronJS, in which case both inline scripts and all modules loaded via <script> tags are considered CLI)
The only case where is does not work is when you preload the top-level script (e.x. nodejs -r cli.js cli.js). This problem cannot be solved by piping (e.x. cat cli.js | nodejs -r cli.js) because that executes the script twice (once as a required module and once as top-level). I do not believe there is any possible fix for this because there is no way to know what the main script will be from inside a preloaded script.
† Theoretically, errors might be thrown from inside of a getter for an object (e.x. if someone were crazy enough to do Object.defineProperty(globalThis, "process", { get(){throw 0} });), however this will never happen under default circumstances for the properties used in the code snippet in any environment.
How can I detect whether my node.js file was called directly from console (windows and unix systems) or loaded using the ESM module import ( import {foo} from 'bar.js')
Such functionality is not exposed. For the moment you should separate your cli and library logic into separate files.
Answer from node.js core contributor devsnek replying to nodejs/help/issues/2420
It's the right answer in my point of view