Develop Reference

Packaging-up Browser/Server CommonJS modules with dependancies

Lets say I'm writing a module in JavaScript which can be used on both the browser and the server (with Node). Lets call it Module. And lets say that that Module would benefit from methods in another module called Dependancy. Both of these modules have been written to be used by both the browser and the server, à la CommonJS style:
module.js
if (typeof module !== 'undefined' && module.exports)
module.exports = Module; /* server */
else
this.Module = Module; /* browser */
dependancy.js
if (typeof module !== 'undefined' && module.exports)
module.exports = Dependancy; /* server */
else
this.Dependancy = Dependancy; /* browser */
Obviously, Dependancy can be used straight-out-of-the-box in a browser. But if Module contains a var dependancy = require('dependency'); directive in it, it becomes more of a hassle to 'maintain' the module.
I know that I could perform a global check for Dependancy within Module, like this:
var dependancy = this.Dependancy || require('dependancy');
But that means my Module has two added requirements for browser installation:
the user must include the dependency.js file as a <script> in their document
and the user must make sure this script is loaded before module.js
Adding those two requirements throws the idea of an easy-going modular framework like CommonJS.
The other option for me is that I include a second, compiled script in my Module package with the dependency.js bundled using browserify. I then instruct users who are using the script in the browser to include this script, while server-side users use the un-bundled entry script outlined in the package.json. This is preferable to the first way, but it requires a pre-compilation process which I would have to run every time I changed the library (for example, before uploading to GitHub).
Is there any other way of doing this that I haven't thought of?

The two answers currently given are both very useful, and have helped me to arrive at my current solution. But, as per my comments, they don't quite satisfy my particular requirements of both portability vs ease-of-use (both for the client and the module maintainer).
What I found, in the end, was a particular flag in the browserify command line interface that can bundle the modules and expose them as global variables AND be used within RequireJS (if needed). Browserify (and others) call this Universal Module Definition (UMD). Some more about that here.
By passing the --standalone flag in a browserify command, I can set my module up for UMD easily.
So...
Here's the package.js for Module:
{
"name": "module",
"version": "0.0.1",
"description": "My module that requires another module (dependancy)",
"main": "index.js",
"scripts": {
"bundle": "browserify --standalone module index.js > module.js"
},
"author": "shennan",
"devDependencies": {
"dependancy": "*",
"browserify": "*"
}
}
So, when at the root of my module, I can run this in the command line:
$ npm run-script bundle
Which bundles up the dependancies into one file, and exposes them as per the UMD methodology. This means I can bootstrap the module in three different ways:
NodeJS
var Module = require('module');
/* use Module */
Browser Vanilla
<script src="module.js"></script>
<script>
var Module = module;
/* use Module */
</script>
Browser with RequireJS
<script src="require.js"></script>
<script>
requirejs(['module.js'], function (Module) {
/* use Module */
});
</script>
Thanks again for everybody's input. All of the answers are valid and I encourage everyone to try them all as different use-cases will require different solutions.

Of course you could use the same module with dependency on both sides. You just need to specify it better. This is the way I use:
(function (name, definition){
if (typeof define === 'function'){ // AMD
define(definition);
} else if (typeof module !== 'undefined' && module.exports) { // Node.js
module.exports = definition();
} else { // Browser
var theModule = definition(), global = this, old = global[name];
theModule.noConflict = function () {
global[name] = old;
return theModule;
};
global[name] = theModule;
}
})('Dependency', function () {
// return the module's API
return {
'key': 'value'
};
});
This is just a very basic sample - you can return function, instantiate function or do whatever you like. In my case I'm returning an object.
Now let's say this is the Dependency class. Your Module class should look pretty much the same, but it should have a dependency to Dependency like:
function (require, exports, module) {
var dependency = require('Dependency');
}
In RequireJS this is called Simplified CommonJS Wrapper: http://requirejs.org/docs/api.html#cjsmodule
Because there is a require statement at the beginning of your code, it will be matched as a dependency and therefore it will either be lazy loaded or if you optimize it - marked as a dependency early on (it will convert define(definition) to define(['Dependency'], definition) automatically).
The only problem here is to keep the same path to the files. Keep in mind that nested requires (if-else) won't work in Require (read the docs), so I had to do something like:
var dependency;
try {
dependency = require('./Dependency'); // node module in the same folder
} catch(err) { // it's not node
try {
dependency = require('Dependency'); // requirejs
} catch(err) { }
}
This worked perfectly for me. It's a bit tricky with all those paths, but at the end of the day, you get your two separate modules in different files which can be used on both ends without any kind of checks or hacks - they have all their dependencies are work like a charm :)

Take a look at webpack bundler.
You can write module and export it via module exports. Then You can in server use that where you have module.export and for browser build with webpack. Configuration file usage would be the best option
module.exports = {
entry: "./myModule",
output: {
path: "dist",
filename: "myModule.js",
library: "myModule",
libraryTarget: "var"
}
};
This will take myModule and export it to myModule.js file. Inside module will be assigned to var (libraryTarget flag) named myModule (library flag).
It can be exported as commonJS module, war, this, function
Since bundling is node script, this flag values can be grammatically set.
Take a look at externals flag. It is used if you want to have special behavior for some dependencies. For example you are creating react component and in your module you want to require it but not when you are bundling for web because it already is there.
Hope it is what you are looking for.

Require.js looking in the wrong path for the nested dependencies

I use WebJars to manage my JavaScript dependencies which means that most of the libraries I use are outside the Require.js base path. The config is created automatically and it works for most libraries. I only have problems with those libraries that call require() to load some inner dependencies (usually just external files) - for example when.js.
This is the require.js config generated for when library:
requirejs.config({"paths":{"when":["/webjars/when-node/3.5.2/when","when"]}});
This file loads properly. But the problem is that it tries to load further files:
...
var timed = require('./lib/decorators/timed');
var array = require('./lib/decorators/array');
var flow = require('./lib/decorators/flow');
var fold = require('./lib/decorators/fold');
...
I would expect require.js to use the location of when.js to determine the correct locations of the other required files, i. e.:
/webjars/when-node/3.5.2/lib/decorators/timed.js
But unfortunately require.js uses instead the location of the main.js file as the base path which obviously results in a lot of 404 errors and the application crashes.
How can I tell require.js to look in the correct subdirectory?

So according to the RequireJS documentation this seems to be the correct behavior. Unlike CommonJS, every require() call is resolved using the base path (it is relative to the base path, not to the location of the file it is called in).
The only way to get around this (as far as I know) is to configure the dependency as a package. The package location is then used for path resolution instead of the general base path. For the mentioned when package, the configuration should look something like this:
requirejs.config({
packages: [
{ name: 'when', location: '/path/to/when', main: 'when' }
]
});
To fix this problem automatically for all my current or future dependencies, I've replaced the Scala Play Framework loading script with my own solution which loads all WebJars as separate packages.
var require = {
callback : function () {
var packages = [];
var shim = {};
[
#for(webJarJson <- org.webjars.RequireJS.getSetupJson(routes.WebJarAssets.at("").url).values()) {
#Html(webJarJson.toString),
}
].forEach(function (webjar) {
if (webjar.paths) {
for (var name in webjar.paths) {
if (webjar.paths.hasOwnProperty(name)) {
packages.push({
name: name,
location: webjar.paths[name][0].replace(/\/[^\/]+$/, ""),
main: webjar.paths[name][1]
});
}
}
}
if (webjar.shim) {
for (var name in webjar.shim) {
if (webjar.shim.hasOwnProperty(name)) {
shim[name] = webjar.shim[name];
}
}
}
});
requirejs.config({
packages: packages,
shim: shim
});
}
}

Gulp/Grunt: Concatenate only necessary JS files?

Wot I got
I have a gulpfile that produces app.min.js and libs.min.js; fairly selfexplanatory:
var dev = {
libs: [
'bower_components/angular/angular.min.js',
'bower_components/angular-foundation/mm-foundation-tpls.min.js',
'bower_components/underscore.string/dist/underscore.string.min.js'
]
};
var build = {
js: 'public/js'
};
gulp.task('libs', function() {
return gulp.src(dev.libs)
.pipe(concat('libs.min.js'))
.pipe(uglify({mangle: false}))
.pipe(gulp.dest(build.js));
});
In this setup, whenever I add or remove a library, I have to manually add it to the dev.libs array (and in the right order, too), then restart Gulp to see the new lib file.
Wot I WANT
I want to be able to concat the js libs I use without having to specifically define them in (array) dev.libs. At the moment if I use return gulp.src('**/*.js'), I believe it will concat every single js file in bower_components, which'd obviously be ridiculous.
Question
Is there a way to automatically load and concat the libraries I need, without having to define them in a gulpfile?

For Bower, you can use the plugin main-bower-files that will parse the content of your bower.json and search for the main file(s) of each of your dependency, so you don't have to declare each lib.
var bowerFiles = require('main-bower-files');
You can then do :
gulp.task('libs', function () {
return gulp.src(bowerFiles())
.pipe(concat('libs.min.js'))
.pipe(uglify({mangle: false}))
.pipe(gulp.dest(build.js));
});

requirejs - combine several files to single js file that not dependent on requirejs

I am writing jQuery plugin that contains a lot of code. Therefore I decided to separate the code and make it more modular for me (the developer). For this I use require.js.
Now I have 6 js files:
utils.js
base-row.jas
a-row.js
b-row.js
my-table.js
main.js
Files 1 to 5 defines JavaScript "classes" and they have dependecies between themselves. The "primary" class that operates all the concert is my-table.js. main.js has dependency only to my-table.js and creates a plugin from it:
require([
'my-table'
], function(MyTable) {
jQuery.fn.myTable = function(options) {
var table = new MyTable(this, options);
this.data('myTable', table);
return this;
};
});
Now I want to create from those files one big js file that contains all the 6 files without any dependency (except jQuery that the user should put reference to it). For this I used r.js (http://requirejs.org/docs/optimization.html) and as a result I got one big js file that depend on require.js (and contains calls to define and require). I followed this: http://requirejs.org/docs/faq-optimization.html#wrap and used almond.js in order to combined all my files for usage that is not dependent on require.js. This works fine.
The problem is why do I need all the define and require method calls and almond.js? Why couldn't the optimizer concatenate only the function results (as describe in this question: Why do concatenated RequireJS AMD modules need a loader?) like this:
(function() {
var utils = «function() {
....
return Utils;
}»();
var baseRow = «function(A) {
....
return BaseRow;
}»(utils);
....
....
var myTable = .....
//<--This is require call and therefore doesn't return a thing
(function(MyTable) {
jQuery.fn.myTable = function(options) {
var table = new MyTable(this, options);
this.data('myTable', table);
return this;
};
})(myTable);
})();
As a result of this process, I decided to check things out and combined manually all the files to one minified file. I end up with a file smaller by 3k then the almond version!
I don't find the logic behind the r.js optimizer creating require.js dependent result. In my case, no one will need to use any of the files, my primary js file is the only consumer. What do you think?

The default value for the findNestedDependencies option in the optimizer is "false", meaning that even after the scripts are optimized, there could still be a nested require or define call that would require a module loader. A loader is also needed for external dependencies.
I agree, however, that if findNestedDependencies is set to "true" and no external dependencies are part of the project, the optimizer should be able to remove its need for a loader.

You can just include the files needed in the file. You can do that with a getScript call.
$.getScript("my_lovely_script.js", function(){
//whatever you want here.
});

JavaScript require() on client side

Is it possible to use require() (or something similar) on client side?
Example
var myClass = require('./js/myclass.js');

You should look into require.js or head.js for this.

I've been using browserify for that. It also lets me integrate Node.js modules into my client-side code.
I blogged about it here: Add node.js/CommonJS style require() to client-side JavaScript with browserify

If you want to have Node.js style require you can use something like this:
var require = (function () {
var cache = {};
function loadScript(url) {
var xhr = new XMLHttpRequest(),
fnBody;
xhr.open('get', url, false);
xhr.send();
if (xhr.status === 200 && xhr.getResponseHeader('Content-Type') === 'application/x-javascript') {
fnBody = 'var exports = {};\n' + xhr.responseText + '\nreturn exports;';
cache[url] = (new Function(fnBody)).call({});
}
}
function resolve(module) {
//TODO resolve urls
return module;
}
function require(module) {
var url = resolve(module);
if (!Object.prototype.hasOwnProperty.call(cache, url)) {
loadScript(url);
}
return cache[url];
}
require.cache = cache;
require.resolve = resolve;
return require;
}());
Beware: this code works but is incomplete (especially url resolving) and does not implement all Node.js features (I just put this together last night).
YOU SHOULD NOT USE THIS CODE in real apps but it gives you a starting point. I tested it with this simple module and it works:
function hello() {
console.log('Hello world!');
}
exports.hello = hello;

I asked myself the very same questions. When I looked into it I found the choices overwhelming.
Fortunately I found this excellent spreadsheet that helps you choice the best loader based on your requirements:
https://spreadsheets.google.com/lv?key=tDdcrv9wNQRCNCRCflWxhYQ

Take a look at requirejs project.

I have found that in general it is recommended to preprocess scripts at compile time and bundle them in one (or very few) packages with the require being rewritten to some "lightweight shim" also at compile time.
I've Googled out following "new" tools that should be able to do it
http://mixu.net/gluejs/
https://github.com/jrburke/almond
https://github.com/component/builder2.js
And the already mentioned browserify should also fit quite well - http://esa-matti.suuronen.org/blog/2013/04/15/asynchronous-module-loading-with-browserify/
What are the module systems all about?
Older Stack Overflow explanation - Relation between CommonJS, AMD and RequireJS?
Detailed discussion of various module frameworks and the require() they need is in Addy Osmani - Writing Modular JavaScript With AMD, CommonJS & ES Harmony

You can create elements to the DOM, which loads items.
Like such:
var myScript = document.createElement('script'); // Create new script element
myScript.type = 'text/javascript'; // Set appropriate type
myScript.src = './js/myclass.js'; // Load javascript file

Simply use Browserify, what is something like a compiler that process your files before it go into production and packs the file in bundles.
Think you have a main.js file that require the files of your project, when you run browserify in it, it simply process all and creates a bundle with all your files, allowing the use of the require calls synchronously in the browser without HTTP requests and with very little overhead for the performance and for the size of the bundle, for example.
See the link for more info: http://browserify.org/

Some answers already - but I would like to point you to YUI3 and its on-demand module loading. It works on both server (node.js) and client, too - I have a demo website using the exact same JS code running on either client or server to build the pages, but that's another topic.
YUI3: http://developer.yahoo.com/yui/3/
Videos: http://developer.yahoo.com/yui/theater/
Example:
(precondition: the basic YUI3 functions in 7k yui.js have been loaded)
YUI({
//configuration for the loader
}).use('node','io','own-app-module1', function (Y) {
//sandboxed application code
//...
//If you already have a "Y" instance you can use that instead
//of creating a new (sandbox) Y:
// Y.use('moduleX','moduleY', function (Y) {
// });
//difference to YUI().use(): uses the existing "Y"-sandbox
}
This code loads the YUI3 modules "node" and "io", and the module "own-app-module1", and then the callback function is run. A new sandbox "Y" with all the YUI3 and own-app-module1 functions is created. Nothing appears in the global namespace. The loading of the modules (.js files) is handled by the YUI3 loader. It also uses (optional, not show here) configuration to select a -debug or -min(ified) version of the modules to load.

Here's a solution that takes a very different approach: package up all the modules into a JSON object and require modules by reading and executing the file content without additional requests.
https://github.com/STRd6/require/blob/master/main.coffee.md
STRd6/require depends on having a JSON package available at runtime. The require function is generated for that package. The package contains all the files your app could require. No further http requests are made because the package bundles all dependencies. This is as close as one can get to the Node.js style require on the client.
The structure of the package is as follows:
entryPoint: "main"
distribution:
main:
content: "alert(\"It worked!\")"
...
dependencies:
<name>: <a package>
Unlike Node a package doesn't know it's external name. It is up to the pacakge including the dependency to name it. This provides complete encapsulation.
Given all that setup here's a function that loads a file from within a package:
loadModule = (pkg, path) ->
unless (file = pkg.distribution[path])
throw "Could not find file at #{path} in #{pkg.name}"
program = file.content
dirname = path.split(fileSeparator)[0...-1].join(fileSeparator)
module =
path: dirname
exports: {}
context =
require: generateRequireFn(pkg, module)
global: global
module: module
exports: module.exports
PACKAGE: pkg
__filename: path
__dirname: dirname
args = Object.keys(context)
values = args.map (name) -> context[name]
Function(args..., program).apply(module, values)
return module
This external context provides some variable that modules have access to.
A require function is exposed to modules so they may require other modules.
Additional properties such as a reference to the global object and some metadata
are also exposed.
Finally we execute the program within the module and given context.
This answer will be most helpful to those who wish to have a synchronous node.js style require statement in the browser and are not interested in remote script loading solutions.

I find the component project giving a much more streamlined workflow than other solutions (including require.js), so I'd advise checking out https://github.com/component/component . I know this is a bit late answer but may be useful to someone.

Here's a light weight way to use require and exports in your web client. It's a simple wrapper that creates a "namespace" global variable, and you wrap your CommonJS compatible code in a "define" function like this:
namespace.lookup('org.mydomain.mymodule').define(function (exports, require) {
var extern = require('org.other.module');
exports.foo = function foo() { ... };
});
More docs here:
https://github.com/mckoss/namespace

The clientside-require library provides an asynchronous load() function that can be used to load any JS file or NPM module (which uses module.exports), any .css file, any .json, any .html, any any other file as text.
e.g.,
npm install clientside-require --save
<script src = '/node_modules/clientside-require/dist/bundle.js'></script>
<script>
load('color-name') // an npm module
.then(color_name=>{
console.log(color_name.blue); // outputs [0, 0, 255]
})
</script>
A really cool part of this project is that inside of any load()ed script, you can use the synchronous require() function the same way you would expect in node.js!
e.g.,
load('/path/to/functionality.js')
and inside /path/to/functionality.js:
var query_string = require("qs") // an npm module
module.exports = function(name){
return qs.stringify({
name:name,
time:new Date()
}
}
That last part, implementing the synchronous require() method, is what enables it to utilize NPM packages built to run on the server.
This module was designed to implement the require functionality as closely as possible in the browser. Disclaimer: I have written this module.

Yes it is very easy to use, but you need to load javascript file in browser by script tag
<script src="module.js"></script>
and then user in js file like
var moduel = require('./module');
I am making a app using electron and it works as expected.