JavaScript requiring libraries

Question

I'm quite new to the world of JavaScript (specially when it comes to libraries). Quite a few of them tell you to use require('libName') as a way to integrate the library on your web page/application. Could someone explain to me how exactly that works and how to implement this? Cause by default require() doesn't work.

Answer 1

JavaScript in the browser doesn't have a require function, this functionality is provided by external libraries following the two most popular specs: CommonJS and AMD. Take a look at RequireJS that plays nice with both patterns.

JavaScript on the server (NodeJS), uses CommonJS spec by default.

Answer 2

Here is a very lightweight require:

var require = function(src, success, failure){
    !function(source, success_cb, failure_cb){
            var script = document.createElement('script');
            script.async = true; script.type = 'text/javascript'; script.src = source;
            script.onload = success_cb || function(e){};
            script.onerror = failure_cb || function(e){};
            (document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(script);
    }(src, success, failure);
}

require('js/jquery.js', function(){
    console.log('jQuery is ready to use');
}, function(){
    console.log("Something went wrong loading this script");
});