Object::filter /for @4ntoin3

Object_filter.js

var obj = {a:1,b:2,c:9,d:10,f:5};

Object.defineProperty(Object.prototype, "filter", {
  value: function(f) {
    return Object.keys(this).reduce(function(m, k) {
      return f(this[k], k, this) ? (m[k] = this[k], m) : m;
    }.bind(this), {});
  },
  enumerable: false,
  writable: true
});

obj.filter(function(v, k, obj){return v >= 5;});
// Object {c: 9, d: 10, f: 5}

Note: writable:true is just here for testing