Returns a reference to the  function that created the instance's prototype.

注意这个属性的值是函数本省的引用，而不是一个包含函数名的字符串。这个值只有对primitive values（例如1，true和"test"等）才是只读的。

Description

All objects inherit a constructor property from their prototype:

var o = {};o.constructor === Object; // truevar a = [];a.constructor === Array; // truevar n = new Number(3);n.constructor === Number; // true

Examples

Displaying the constructor of an object

The following example creates a prototype, Tree, and an object of that type, theTree. The example then displays the constructor property for the object theTree.

function Tree(name) {  this.name = name;}var theTree = new Tree('Redwood');console.log('theTree.constructor is ' + theTree.constructor);

This example displays the following output:

theTree.constructor is function Tree(name) {  this.name = name;}

Changing the constructor of an object

The following example shows how to modify constructor value of generic objects. Only true, 1and "test" will not be affected as they have read-only native constructors. This example shows that it is not always safe to rely on the constructor property of an object.

function Type () {}var types = [  new Array(),  [],  new Boolean(),  true,             // remains unchanged  new Date(),  new Error(),  new Function(),  function () {},  Math,  new Number(),  1,                // remains unchanged  new Object(),  {},  new RegExp(),  /(?:)/,  new String(),  'test'            // remains unchanged];for (var i = 0; i < types.length; i++) {  types[i].constructor = Type;  types[i] = [types[i].constructor, types[i] instanceof Type, types[i].toString()];}console.log(types.join('\n'));

 

This example displays the following output:

function Type() {},false,function Type() {},false,function Type() {},false,falsefunction Boolean() {    [native code]},false,truefunction Type() {},false,Mon Sep 01 2014 16:03:49 GMT+0600function Type() {},false,Errorfunction Type() {},false,function anonymous() {}function Type() {},false,function () {}function Type() {},false,[object Math]function Type() {},false,0function Number() {    [native code]},false,1function Type() {},false,[object Object]function Type() {},false,[object Object]function Type() {},false,/(?:)/function Type() {},false,/(?:)/function Type() {},false,function String() {    [native code]},false,test