class-extend.js

function classExtend(subClass, superClass) {
  for (var property in superClass) {
    if (superClass.hasOwnProperty(property)) {
      subClass[property] = superClass[property];
    }
  }

  function constructor() {
    this.constructor = subClass;
  }

  constructor.prototype = superClass.prototype;
  subClass.prototype = new constructor();
}

class-extend.min.js

function classExtend(a,b){function d(){this.constructor=a}for(var c in b)b.hasOwnProperty(c)&&(a[c]=b[c]);d.prototype=b.prototype,a.prototype=new d}