How do I use requireJS and jQuery together?

2019-01-08 03:17发布

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问题:

I would like to use requireJS and I am using jQuery. I don't want to use the combined version of requireJS and jQuery since I am not using the latest jQuery version. What is the best way for me to work with requireJS?

回答1:

That is my exact question too! I also must use an older jQuery, but also more "traditional" javascript libraries. What is the best technique to do that? (I may edit your question to make it more broad if you don't mind.) Here is what I learned.

RequireJS author, James Burke, explained the advantages of the combined RequireJS + jQuery file. You get two things.

A module, jquery, is available, and it's the jQuery object. This is safe:

// My module depends on jQuery but what if $ was overwritten?
define(["jquery"], function($) {
  // $ is guaranteed to be jQuery now */
})

jQuery is already loaded before any require() or define() stuff. All modules are guaranteed that jQuery is ready. You don't even need the require/order.js plugin since jQuery was basically hard-coded to load first.

To me, #2 isn't very helpful. Most real applications have many .js files that must load in the right order—sad but true. As soon as you need Sammy or Underscore.js, the combined RequireJS+jQuery file doesn't help.

My solution is to write simple RequireJS wrappers that load my traditional scripts using the "order" plugin.

Example

Suppose my app has these components (by dependency).

My app, greatapp
- greatapp depends on a custom jquery (old version I must use)
- greatapp depends on my_sammy (SammyJS plus all its plugins I must use). These must be in order
  1. my_sammy depends on jquery (SammyJS is a jQuery plugin)
  2. my_sammy depends on sammy.js
  3. my_sammy depends on sammy.json.js
  4. my_sammy depends on sammy.storage.js
  5. my_sammy depends on sammy.mustache.js

In my mind, everything above that ends with .js is a "traditional" script. Everything without .js is a RequireJS plugin. The key is: high-level stuff (greatapp, my_sammy) are modules, and at deeper levels, it falls back to traditional .js files.

Booting

It all starts with a booter telling RequireJS how to start.

<html>
  <head>
    <script data-main="js/boot.js" src="js/require.js"></script>
  </head>
</html>

In js/boot.js I put only the config and how to start the application.

require( // The "paths" maps module names to actual places to fetch the file.
         // I made modules with simple names (jquery, sammy) that will do the hard work.
         { paths: { jquery: "require_jquery"
                  , sammy : "require_sammy"
                  }
         }

         // Next is the root module to run, which depends on everything else.
       , [ "greatapp" ]

         // Finally, start my app in whatever way it uses.
       , function(greatapp) { greatapp.start(); }
       );

Main Application

In greatapp.js I have a normal looking module.

define(["jquery", "sammy"], function($, Sammy) {
  // At this point, jQuery and SammyJS are loaded successfully.
  // By depending on "jquery", the "require_jquery.js" file will run; same for sammy.
  // Those require_* files also pass jQuery and Sammy to here, so no more globals!

  var start = function() {
    $(document).ready(function() {
      $("body").html("Hello world!");
    })
  }

  return {"start":start};
}

RequireJS module wrappers around traditional files

require_jquery.js:

define(["/custom/path/to/my/jquery.js?1.4.2"], function() {
  // Raw jQuery does not return anything, so return it explicitly here.
  return jQuery;
})

require_sammy.js:

// These must be in order, so use the "order!" plugin.
define([ "order!jquery"
       , "order!/path/to/custom/sammy/sammy-0.6.2-min.js"
       , "order!/path/to/custom/sammy/plugins/sammy.json-0.6.2-min.js"
       , "order!/path/to/custom/sammy/plugins/sammy.storage-0.6.2-min.js"
       , "order!/path/to/custom/sammy/plugins/sammy.mustache-0.6.2-min.js"
       ]

       , function($) {
           // Raw sammy does not return anything, so return it explicitly here.
           return $.sammy;
         }
      );

回答2:

This question is at least two years old now, but I noticed this is a problem still with RequireJS 2.0 (require-jquery.js uses jQuery 1.8.0, but the latest version is 1.8.2).

If you happen to see this question, note that require-jquery.js is now just require.js and jquery.js, mashed together. You can just edit require-jquery.js and replace the the jQuery parts with a newer version.

Update (May 30, 2013): Now that RequireJS has paths and shim, there is a new way to import jQuery and jQuery plugins, and the old method is no longer necessary nor recommended. Here is an abridged version of the current method:

requirejs.config({
    "paths": {
      "jquery": "//ajax.googleapis.com/ajax/libs/jquery/2.0.0/jquery.min"
    }
});

define(["jquery"], function($) {
    $(function() {
    });
});

See http://requirejs.org/docs/jquery.html for more info.

回答3:

I've found the best approach is to keep jQuery outside of my RequireJS build.

Just include jquery.min.js in your HTML. Then, make a jquery.js file with something like this...

define([], function() {
    return window.$;
});

回答4:

Found JasonSmith's anwer tremendously helpful, probably more so than the RequireJS's documentation.

However, there is way to optimize on it to avoid having separate AJAX requests for (tiny) define-declaring modules ("require_jquery" "require_sammy"). I would suspect r.js would do it at optimization stage, but you can do that ahead of time in order not to fight with Path, BaseURI system.

index.html:

<html>
  <head>
    <script data-main="js/loader.js" src="js/require.js"></script>
  </head>
</html>

loader.js:

// We are going to define( dependencies by hand, inline.
// There is one problem with that through (inferred from testing):
// Dependencies are starting to load (and execute) at the point of declaring the inline
// define, not at the point of require(
// So you may want to nest the inline-defines inside require( 
// this is, in a way, short replacement for Order plug in, but allows you to use
// hand-rolled defines, which the Order plug in, apparently does not allow.

var jQueryAndShims = ['jquery']

if(window.JSON == null){
    jQueryAndShims.push('json2')
    define(
        'json2'
        , ['js/libs/json2.min.js']
        , function() {
            return window.JSON
        }
    )
}
// will start loading the second we define it.
define(
    'jquery'
    , ['js/libs/jquery_custom.min.js']
    , function() {
        // we just pick up global jQuery here. 
        // If you want more than one version of jQuery in dom, read a more complicated solution discussed in
        // "Registering jQuery As An Async-compatible Module" chapter of
        // http://addyosmani.com/writing-modular-js/
        return window.jQuery 
    }
)

// all inline defines for resources that don't rely on other resources can go here.

// First level require(
// regardless of depends nesting in 'myapp' they will all start downloading 
// at the point of define( and exec whenever they want, 
// async in many browsers. Actually requiring it before the nested require makes
// sure jquery had *executed and added jQuery to window object* before
// all resolved depends (jquery plugins) start firing.
require(jQueryAndShims, function($) {

    // will start loading the second we define it.        
    define(
        'sammy_and_friends'
        , ['jquery','js/libs/jquery_pluginone.min.js','js/libs/jquery_plugintwo.min.js','js/libs/sammy.min.js']
        , function($) {
            // note, all plugins are unaltered, as they are shipped by developers.
            // in other words, they don't have define(.. inside.
            // since they augment global $ (window.jQuery) anyway, and 'jquery' define above picks it up
            // , we just keep on returning it.
            // Sammy is attached to $ as $.sammy, so returning just Sammy makes little sense
            return $
        }
    )

    // second level require - insures that Sammy (and other jQuery plugins) - 'sammy_and_friends' - is
    // loaded before we load Sammy plugins. I normally i would inline all sammy plugins i need 
    // (none, since i use none of them preferring jQuery's direct templating API
    // and no other Sammy plug in is really of value. )  right into sammy.js file. 
    // But if you want to keep them separate:
    require(['sammy_and_friends'], function() {

        // will start loading the second we define it.
        define(
            'sammy_extended'
            , ['sammy_and_friends','js/libs/sammy_pluginone.min.js','js/libs/sammy_plugintwo.min.js']
            , function($) {
                // as defined above, 'sammy_and_friends' actually returns (globall) jQuery obj to which
                // Sammy is attached.  So we continue to return $
                return $
            }
        )
        // will start loading the second we define it.
        define(
            'myapp'
            , ['sammy_extended', 'js/myapplication_v20111231.js'] 
            , function($, myapp_instantiator) {
                // note, myapplication may, but does not have to contain RequireJS-compatible define
                // that returns something. However, if it contains something like 
                // "$(document).ready(function() { ... " already it MAY fire before 
                // it's depends - 'sammy_extended' is fully loaded.
                // Insdead i recommend that myapplication.js returns a generator 
                // (app-object-generating function pointer)
                // that takes jQuery (with all loaded , applied plugins) 
                // The expectation is that before the below return is executed, 
                // all depends are loaded (in order of depends tree)
                // You would init your app here like so:
                return myapp_instantiator($)
                // then "Run" the instance in require( as shown below
            }
        )

        // Third level require - the one that actually starts our application and relies on
        // dependency pyramid stat starts with jQuery + Shims, followed by jQuery plugins, Sammy, 
        // followed by Sammy's plugins all coming in under 'sammy_extended'
        require(['jquery', 'myapp'], function($, myappinstance) {
            $(document).ready(function() {myappinstance.Run()})
        })
    }) // end of Second-level require
}) // end of First-level require

finally, myapplication.js:

// this define is a double-wrap.
// it returns application object instantiator that takes in jQuery (when it's available) and , then, that
// instance can be "ran" by pulling .Run() method on it.
define(function() {
    // this function does only two things:
    // 1. defines our application class 
    // 2. inits the class and returns it.
    return function($) {
        // 1. defining the class
        var MyAppClass = function($) {
            var me = this
            this._sammy_application = $.sammy(function() {
                this.raise_errors = true
                this.debug = true
                this.run_interval_every = 300
                this.template_engine = null
                this.element_selector = 'body'
                // ..
            })
            this._sammy_application.route(...) // define your routes ets...
            this.MyAppMethodA = function(blah){log(blah)}  // extend your app with methods if you want
            // ...
             // this one is the one we will .Run from require( in loader.js
            this.Run = function() {
                me._sammy_application.run('#/')
            }
        }
        // 2. returning class's instance
        return new MyAppClass($) // notice that this is INITED app, but not started (by .Run) 
        // .Run will be pulled by calling code when appropriate
    }
})

This structure (loosely replaces (duplicates?) RequireJS's Order plugin, but) allows you to prune the number of files you need to AJAX, adding more control to definition of depends and depend tree.

There is also a large bonus to loading jQuery separately (which usually comes at 100k) - you can control caching at server, or cache jQuery into browser's localStorage. Take a look at AMD-Cache project here https://github.com/jensarps/AMD-cache then change the define( statements to include "cache!": and it will be (forever :) ) stuck in user's browser.

define(
    'jquery'
    , ['cache!js/libs/jquery_old.min.js']
    , function() {
        // we just pick up global jQuery here. 
        // If you want more than one version of jQuery in dom, read a more complicated solution discussed in
        // "Registering jQuery As An Async-compatible Module" chapter of
        // http://addyosmani.com/writing-modular-js/
        return window.jQuery 
    }
)

Note about jQuery 1.7.x+ It no longer attaches itself to window object, so the above will NOT work with unmodified jQuery 1.7.x+ file. There you must customize your jquery**.js to include this before the closing "})( window );":

;window.jQuery=window.$=jQuery

If you have "jQuery undefined" errors in console, it's a sign jQuery version you are using is not attaching itself to window.

Code license: Public domain.

Disclosures: JavaScript above smells of "pseudo-code" as it is a paraphrasing (hand-pruning) of much more detailed production code. Code as presented above is not guaranteed to work and was NOT tested to work as presented. Audit, test it. Semicolons omitted on purpose, as they are not required per JS spec and code looks better without them.

回答5:

In addition to jhs's answer, see the more recent instructions on the require-jquery github page from the README.md file. It covers both the simplest approach of using a combined jquery/require.js file and also how to use a separate jquery.js.