object inheritance vs object composition

Benchmark created by foreach vs each on September 3, 2011

Preparation HTML

<script>
// ## [Github Repo](https://github.com/Raynos/pd)

// pd converts all the values of the properties into propertydescriptors
var pd = function _pd(obj) {
    var keys = Object.keys(obj);
    var o = {};
    keys.forEach(function _each(key) {
        var pd = Object.getOwnPropertyDescriptor(obj, key);
        o[key] = pd;
    });
    return o;
};

// merges merges all objects passed in. The later objects take preference in clashes
pd.merge = function _merge() {
    var o = {};
    for (var k in arguments) {
        var obj = arguments[k];
        Object.keys(obj).forEach(function _each(key) {
            o[key] = obj[key];
        });
    }
    return o;
};

// object is an Object.create shortcut. Consider it an improved object literal.
pd.object = function _obj(o) {
    return Object.create(Object.prototype, pd(o));
};

var addPropertyProxy = function(target, source, key) {
    Object.defineProperty(target, key, {
        "get": function _get() {
            return source[key];    
        },
        "enumerable": true,
        "configurable": true  
    }); 
};

pd.proxy = function _proxy() {
    var o = {};
    for (var k in arguments) {
        var obj = arguments[k];
        Object.keys(obj).forEach(function _each(key) {
            addPropertyProxy(o, obj, key);
        });  
    }
    return o;
};

if ("undefined" !== typeof module && module.exports) {
    module.exports = pd;
} else {
    window.pd = pd;
}
</script>

<script>
  var lower  = {
    "foo": "bar"
  };
  
  var upper = {
    "bar": "foo"
  };
  
  var combined = Object.create(lower,  pd(upper));
  
  var c1 = Object.create(combined);
  
  var c2 = Object.create(pd.merge(lower, upper));
  
  var c3 = Object.create(pd.proxy(lower, upper));
  
  var o1 = Object.create(c1);
  var o2 = Object.create(c2);
  var o3 = Object.create(c3);
</script>

Test runner

o1.foo;

o2.foo;

o3.foo

Revisions

You can edit these tests or add more tests to this page by appending /edit to the URL.

• Revision 1: published by foreach vs each on September 3, 2011
• Revision 2: published on May 6, 2013