extend function, merges object properties into first passed

extend.js

  function extend() {
    var args = Array.prototype.slice.call(arguments);
    var base = args.slice(0, 1)[0];
    var objs = args.slice(1);
    for (var i = 0; i < objs.length; i++) {
      for (var p in objs[i]) {
        if (!base[p]) base[p] = objs[i][p];
      }
    }
    return base;
  }
  
  /**
   * var extended = extend({}, { a: "a" }, { b: "b" });
   * --> { a: "a", b: "b" }
   * 
   * var extended = extend({ a: "a" }, { d: "d", e: "e" }, { d: "d" } );
   * --> { a: "a", d: "d", e: "e" }
   * /