I'm having an issue with RequireJS. Essentially, I'm not able to access a function defined inside another file from another one.
I need to do that because I want to export a given subset of functions like
define('submodule', [], function() { let myFunction1 = function(){ return "Hello"; } let myFunction2 = function(){ return " From"; } let myFunction3 = function(){ return " Submodule!"; } return { myFunction1 : myFunction1, myFunction2 : myFunction2, myFunction3 : myFunction3, }; }); And accessing them from another file
define('main', ['config', 'sub1', 'sub2', 'submodule'], function(config, sub1, sub2, submodule) { //Config alert(config.conf); //Submodule let callSubmodule = function() { alert(submodule.myFunction1() + submodule.myFunction2() + submodule.myFunction3()); } //sub1 let callSub1 = function() { alert(sub1.myFunction1()); } //sub2 let callSub2 = function() { alert(sub2.myFunction1()); } }); The fact is that usually I'm able to do this with sub1 and sub2, but, with submodule, I simply can't. I think it's somehow caused by the dependencies in require.config.js.
My require.config.js:
require(['common'], function () { //contains vendors require(['config'], function () { //contains a js config file require(['main'], function () { //main file require(['sub1', 'sub2'], function () { //some subfiles require(['submodule']); }); }); }); }); For submodule.myFunction1() and othe two related functions I'm getting:
Uncaught (in promise) TypeError: Cannot read property 'myFunction1' of undefined
This is weird since I'm able to do that in other situations and I really can't understand why this is happening. For instance, I'm able to call sub1 and sub2 functions from main and other files but not submodule in particular.
Index.html
//Taken from Plunker . . . <script data-main="common" data-require="require.js@2.1.20" data-semver="2.1.20" src="http://requirejs.org/docs/release/2.1.20/minified/require.js"></script> <script src="require.config.js"></script> . . . <button onclick = "callSubmodule()">Call Submodule</button> <button onclick = "callSub1()">Call Sub1</button> <button onclick = "callSub2()">Call Sub2</button> common.js contains vendors, here's just an example
requirejs.config({ baseUrl : "", paths : { "jquery" : "http://code.jquery.com/jquery-latest.min.js" } }); sub1.js
define('sub1', ['submodule'], function(submodule) { let myFunction1 = function(){ return "called sub1"; } return { myFunction1 : myFunction1 }; }); sub2.js
define('sub2', ['submodule'], function(submodule) { let myFunction1 = function(){ return "called sub2"; } return { myFunction1 : myFunction1 }; }); I set up a Plunker with @SergGr help that tries to replicate application's structure but all the modules get undefined on click. On the real application this does not happen.
How can I solve this?
4 Answers
Answers 1
This is your code:
define('main', ['submodule'], function(submod) { console.log(submodule.myFunction()); }); You have submod in the parameter list. But you then try to access submodule. Note that you return the function straight from your module (return myFunction), so your module has the value of the function myFunction and thus the module is what you should call. The code should be:
define('main', ['submodule'], function(submod) { console.log(submod()); }); Answers 2
I Managed to solve this issue. Essentially, it was caused by a circular-dependency between the modules. So, a needed b and b needed a leading to one of them being undefined on the dependency resolution.
I found a solution to that on the answer provided by @jgillich at requirejs module is undefined.
So, I managed to solve using, in main
define('main', ['config', 'sub1', 'sub2', 'require'], function(config, sub1, sub2, submodule, require) { //Config alert(config.conf); //Submodule let callSubmodule = function() { alert(require('submodule').myFunction1() + require('submodule').myFunction2() + require('submodule').myFunction3()); } }); As @jgillich said:
If you define a circular dependency ("a" needs "b" and "b" needs "a"), then in this case when "b"'s module function is called, it will get an undefined value for "a". "b" can fetch "a" later after modules have been defined by using the require() method (be sure to specify require as a dependency so the right context is used to look up "a"):
//Inside b.js: 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(); } } ); Answers 3
The way you've named your modules I would expect they all came from a require config file. I would not expect that requirejs would know how to load those files without some sort of explicit compilation process. I also suspect that your server is returning something due to a 404 that JS is almost able to interpret without exploding.
Your setup seems and naming scheme seems quite strange. If you have the ability to start from scratch below are my recommendations.
Recommendations:
- I'm noticing that you're using absolute paths. I highly recommend using relative paths for everything. There are many reasons for this.
- Your data-main should be what you call "require.config.js". Your common.js is actually a require.config.js.
- You load require.config.js (which is your main) separately using a script tag. You can do this but it's strange.
- You can use the "commonjs" style syntax to require files without needing to use the array to define all your dependencies. I recommend that.
This is my recommendation for a set-up:
index.html
<script src="/js/config.js" /> <script src="http://requirejs.org/docs/release/2.1.20/minified/require.js" /> <script> require('/js/main', function(main) { main({}); }); </script> /js/config.js
// setting requirejs to an object before its loaded will cause requirejs to use it as the config window.requirejs = { baseUrl : "/", paths : { "jquery" : "http://code.jquery.com/jquery-latest.min.js" } }; /js/main.js
define(function(require) { const sum = require('./sum'); return (a, b) => sum(a, b); }); /js/sum.js
define(function(require) { return (a, b) => a + b; }); Answers 4
Update (March 02, 2017)
Your plunker obviously will not work because you have direct calls from HTML to your module functions.
<button onclick = "callSubmodule()">Call Submodule</button> <button onclick = "callSub1()">Call Sub1</button> <button onclick = "callSub2()">Call Sub2</button> RequireJS doesn't work that way. One of key purposes of RequireJS is to provide modules isolation and thus it just can't work that way: imagine if several different modules had functions callSubmodule.
To the best of my knowledge there is no way to bind calls from HTML back to the code in a RequireJS module, it should be other way around: module binds to HTML. And if you fix those issues, everything works fine for me as you can see at this fork of your plunker.
Old Answer
The bug is in your subModule.js
define('submodule', [], function() { let myFunction = function(){ return "Hello"; } //return myFunction; // old, wrong return { myFunction: myFunction }; }); Even if you want to return just 1 function you should not return it as is, you should wrap it into an object and give it an explicit name.
P.S. if this is not your real issuse, please provide us real Minimal, Complete, and Verifiable example
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