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Object.create 方法
Object.create(proto[, propertiesObject])
The Object.create() method creates a new object with the specified prototype object and properties.
第1个参数是该对象的 prototype, 第2个参数和 Object.defineProperties 第2个参数类似
var o; // create an object with null as prototype o = Object.create(null); o = {}; // is equivalent to: o = Object.create(Object.prototype); function Constructor() {} o = new Constructor(); // is equivalent to: o = Object.create(Constructor.prototype); // Of course, if there is actual initialization code // in the Constructor function, // the Object.create() cannot reflect it // Example where we create an object with a couple of // sample properties. (Note that the second parameter // maps keys to *property descriptors*.) o = Object.create(Object.prototype, { // foo is a regular ‘value property‘ foo: { writable: true, configurable: true, value: ‘hello‘ }, // bar is a getter-and-setter (accessor) property bar: { configurable: false, get: function() { return 10; }, set: function(value) { console.log(‘Setting `o.bar` to‘, value); } /* with ES5 Accessors our code can look like this get function() { return 10; }, set function(value) { console.log(‘Setting `o.bar` to‘, value); } */ } }); // Create a new object whose prototype is a new, empty // object and add a single property ‘p‘, with value 42. o = Object.create({}, { p: { value: 42 } }); // by default properties ARE NOT writable, // enumerable or configurable: o.p = 24; o.p; // 42 o.q = 12; for (var prop in o) { console.log(prop); } // ‘q‘ delete o.p; // false // to specify an ES3 property o2 = Object.create({}, { p: { value: 42, writable: true, enumerable: true, configurable: true } });
Polyfill
if (typeof Object.create != ‘function‘) { Object.create = (function(undefined) { var Temp = function() {}; return function (prototype, propertiesObject) { if(prototype !== Object(prototype)) { throw TypeError( ‘Argument must be an object, or null‘ ); } Temp.prototype = prototype || {}; var result = new Temp(); Temp.prototype = null; if (propertiesObject !== undefined) { Object.defineProperties(result, propertiesObject); } // to imitate the case of Object.create(null) if(prototype === null) { result.__proto__ = null; } return result; }; })(); }
参考地址:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/create
Object.create 方法
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