John Resig, the creator of jQuery, has created this JavaScript inheritance code. I am still using it now to simplify several aspects of my Hound CMS.
/* Simple JavaScript Inheritance
* By John Resig https://johnresig.com/
* MIT Licensed.
*/
// Inspired by base2 and Prototype
(function() {
var initializing = false,
fnTest = /xyz/.test(function() {xyz;}) ? /\b_super\b/ : /.*/;
// The base Class implementation (does nothing)
this.Class = function(){};
// Create a new Class that inherits from this class
Class.extend = function(prop) {
var _super = this.prototype;
// Instantiate a base class (but only create the instance, don't run the init constructor)
initializing = true;
var prototype = new this();
initializing = false;
// Copy the properties over onto the new prototype
for (var name in prop) {
// Check if we're overwriting an existing function
prototype[name] = typeof prop[name] == "function" && typeof _super[name] == "function" && fnTest.test(prop[name]) ? (function(name, fn) {
return function() {
var tmp = this._super;
// Add a new ._super() method that is the same method but on the super-class
this._super = _super[name];
// The method only need to be bound temporarily, so we remove it when we're done executing
var ret = fn.apply(this, arguments);
this._super = tmp;
return ret;
};
})(name, prop[name]) : prop[name];
}
// The dummy class constructor
function Class() {
// All construction is actually done in the init method
if (!initializing && this.init) {
this.init.apply(this, arguments);
}
}
// Populate our constructed prototype object
Class.prototype = prototype;
// Enforce the constructor to be what we expect
Class.constructor = Class;
// And make this class extendable
Class.extend = arguments.callee;
return Class;
};
})();Usage:
var Person = Class.extend({
init: function(isDancing) {
this.dancing = isDancing;
},
dance: function() {
return this.dancing;
}
});
var Ninja = Person.extend({
init: function() {
this._super(false);
},
dance: function() {
// Call the inherited version of dance()
return this._super();
},
swingSword: function() {
return true;
}
});
var p = new Person(true);
p.dance(); // => true
var n = new Ninja();
n.dance(); // => false
n.swingSword(); // => true
// Should all be true
p instanceof Person && p instanceof Class &&
n instanceof Ninja && n instanceof Person && n instanceof ClassThe original article, complete with explanations and examples is here: https://johnresig.com/blog/simple-javascript-inheritance/.
Ciprian Popescu
Technical SEO Specialist, JavaScript Programmer and Senior Full Stack Developer. On a quest to experiment with Canvas, WebGL, JavaScript, SEO and WordPress, among many other things. Founder of WPDublin and SpeedFactor, co-organizer of Dublin WordPress Meetup group.
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