Simple class abstraction in js

README.md

Simple js class abstraction

Basically it is backbones self-propegating extend method, slightly hacked up to allow the definition of __name__. Defining this means that you will never end up seeing child when looking at your class in the dev tools. Also adds a define method for creating singletons.

class.js

  var extend = function(protoProps, staticProps){
    var parent = this;
    var child;

    var nameProp = ((staticProps && staticProps.nameProp) || this.nameProp);

    if (protoProps) {
      var name = (protoProps[nameProp] || this[nameProp]);
      var constructor = protoProps.hasOwnProperty('constructor') ? protoProps.constructor : this;

      protoProps = _.extend(protoProps, { constructor: namedConstructor(name, constructor) });
    }

    if(protoProps && _.has(protoProps, 'constructor')){
      child = protoProps.constructor;
    } else{
      child = function(){
        return parent.apply(this, arguments);
      };
    }
    _.extend(child, parent, staticProps);

    var Surrogate = function(){
      this.constructor = child;
    };
    Surrogate.prototype = parent.prototype;
    child.prototype = new Surrogate;

    if(protoProps) _.extend(child.prototype, protoProps);

    child.__super__ = parent.prototype;

    return child;
  };

  var Class = function(){ this.initialize.apply(this, arguments) };

  Class.nameProp = '__name__';
  Class.__name__ = 'Class';
  Class.prototype.initialize = function(){};

  Class.extend = extend;
  Class.define = function(definition){
    var klass = this.extend(definition);
    return new klass();
  };

  function namedConstructor(name, constructor) {
    var fn = new Function('constructor', 'return function ' + name + '(){ '
      + 'constructor.apply(this, arguments) '
      + '};');
    return fn(constructor);
  }

  return Class;

usage.js

  var Singleton = Class.define({
    foo: function(){
      return "there can be only one!";
    }
  });
  
  Singleton.foo(); //=> "there can be only one!"
  
  var Foo = Class.extend({
    __name__: 'Foo'
  });