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As part of deep object cloning code we loop over props of object (Object, or Array) for-in is known to pickup non-itsOwnProperty keys, so testing with Object.keys(o).forEach(
// Object.keys shim.
if(!Object.keys) Object.keys = function(o){
if (o !== Object(o))
throw new TypeError('Object.keys called on non-object');
var ret=[],p;
for(p in o) if(Object.prototype.hasOwnProperty.call(o,p)) ret.push(p);
return ret;
}
// Array.prototype.forEach shim.
// Production steps of ECMA-262, Edition 5, 15.4.4.18
// Reference: http://es5.github.com/#x15.4.4.18
if ( !Array.prototype.forEach ) {
Array.prototype.forEach = function( callback, thisArg ) {
var T, k;
if ( this == null ) {
throw new TypeError( " this is null or not defined" );
}
// 1. Let O be the result of calling ToObject passing the |this| value as the argument.
var O = Object(this);
// 2. Let lenValue be the result of calling the Get internal method of O with the argument "length".
// 3. Let len be ToUint32(lenValue).
var len = O.length >>> 0; // Hack to convert O.length to a UInt32
// 4. If IsCallable(callback) is false, throw a TypeError exception.
// See: http://es5.github.com/#x9.11
if ( {}.toString.call(callback) != "[object Function]" ) {
throw new TypeError( callback + " is not a function" );
}
// 5. If thisArg was supplied, let T be thisArg; else let T be undefined.
if ( thisArg ) {
T = thisArg;
}
// 6. Let k be 0
k = 0;
// 7. Repeat, while k < len
while( k < len ) {
var kValue;
// a. Let Pk be ToString(k).
// This is implicit for LHS operands of the in operator
// b. Let kPresent be the result of calling the HasProperty internal method of O with argument Pk.
// This step can be combined with c
// c. If kPresent is true, then
if ( k in O ) {
// i. Let kValue be the result of calling the Get internal method of O with argument Pk.
kValue = O[ k ];
// ii. Call the Call internal method of callback with T as the this value and
// argument list containing kValue, k, and O.
callback.call( T, kValue, k, O );
}
// d. Increase k by 1.
k++;
}
// 8. return undefined
};
}
// clone method A
Object.prototype.cloneA = function() {
var fn = function (o, cloner){
if(o == null || typeof(o) != 'object') return o
var no = new o.constructor()
for(var key in o) no[key] = cloner(o[key], cloner)
return no;
}
return fn(this, fn)
}
// clone method B
Object.prototype.cloneB = function() {
var fn = function (o, cloner){
if(o == null || typeof(o) != 'object') return o
var no = new o.constructor()
Object.keys(o).forEach(function(e){this[e] = cloner(o[e], cloner)},no)
return no;
}
return fn(this, fn)
}
var o = {a:'a',b:true,c:[1,2,3]}
Ready to run.
Test | Ops/sec | |
---|---|---|
ForIn |
| ready |
forEach |
| ready |
You can edit these tests or add more tests to this page by appending /edit to the URL.