Object.create() 方法用于创建一个新对象，使用现有的对象来作为新创建对象的原型（prototype）。
js
const person = {
isHuman: false,
printIntroduction: function() {
console.log(`My name is ${this.name}. Am I human? ${this.isHuman}`);
}
};
const me = Object.create(person);
me.name = 'Matthew'; // "name" is a property set on "me", but not on "person"
me.isHuman = true; // inherited properties can be overwritten
me.printIntroduction();
// expected output: "My name is Matthew. Am I human? true"
person.printIntroduction();
// > "My name is undefined. Am I human? false"const person = {
isHuman: false,
printIntroduction: function() {
console.log(`My name is ${this.name}. Am I human? ${this.isHuman}`);
}
};
const me = Object.create(person);
me.name = 'Matthew'; // "name" is a property set on "me", but not on "person"
me.isHuman = true; // inherited properties can be overwritten
me.printIntroduction();
// expected output: "My name is Matthew. Am I human? true"
person.printIntroduction();
// > "My name is undefined. Am I human? false"语法
js
Object.create(proto)
Object.create(proto, propertiesObject)Object.create(proto)
Object.create(proto, propertiesObject)使用 null 原型的对象
以 null 为原型的对象存在不可预期的行为，因为它未从 Object.prototype 继承任何对象方法。
特别是在调试时，因为常见的对象属性的转换/检测工具可能会产生错误或丢失信息（特别是在静默模式，会忽略错误的情况下）。
非常纯净。
例如，缺少 Object.prototype.toString() 方法通常会使调试变得非常困难：
js
const normalObj = {}; // create a normal object
const nullProtoObj = Object.create(null); // create an object with "null" prototype
console.log("normalObj is: " + normalObj); // shows "normalObj is: [object Object]"
console.log("nullProtoObj is: " + nullProtoObj); // throws error: Cannot convert object to primitive value
alert(normalObj); // shows [object Object]
alert(nullProtoObj); // throws error: Cannot convert object to primitive value
// 其他方法同样失败
normalObj.valueOf() // shows {}
nullProtoObj.valueOf() // throws error: nullProtoObj.valueOf is not a function
normalObj.hasOwnProperty("p") // shows "true"
nullProtoObj.hasOwnProperty("p") // throws error: nullProtoObj.hasOwnProperty is not a function
normalObj.constructor // shows "Object() { [native code] }"
nullProtoObj.constructor // shows "undefined"
// 我们可以为以 null 为原型的对象添加 `toString` 方法，类似于这样：
nullProtoObj.toString = Object.prototype.toString; // since new object lacks toString, add the original generic one back
console.log(nullProtoObj.toString()); // shows "[object Object]"
console.log("nullProtoObj is: " + nullProtoObj); // shows "nullProtoObj is: [object Object]"const normalObj = {}; // create a normal object
const nullProtoObj = Object.create(null); // create an object with "null" prototype
console.log("normalObj is: " + normalObj); // shows "normalObj is: [object Object]"
console.log("nullProtoObj is: " + nullProtoObj); // throws error: Cannot convert object to primitive value
alert(normalObj); // shows [object Object]
alert(nullProtoObj); // throws error: Cannot convert object to primitive value
// 其他方法同样失败
normalObj.valueOf() // shows {}
nullProtoObj.valueOf() // throws error: nullProtoObj.valueOf is not a function
normalObj.hasOwnProperty("p") // shows "true"
nullProtoObj.hasOwnProperty("p") // throws error: nullProtoObj.hasOwnProperty is not a function
normalObj.constructor // shows "Object() { [native code] }"
nullProtoObj.constructor // shows "undefined"
// 我们可以为以 null 为原型的对象添加 `toString` 方法，类似于这样：
nullProtoObj.toString = Object.prototype.toString; // since new object lacks toString, add the original generic one back
console.log(nullProtoObj.toString()); // shows "[object Object]"
console.log("nullProtoObj is: " + nullProtoObj); // shows "nullProtoObj is: [object Object]"实现继承
js
// Shape - 父类
function Shape() {
this.x = 0;
this.y = 0;
}
// 父类方法
Shape.prototype.move = function(x, y) {
this.x += x;
this.y += y;
console.info('Shape moved.');
};
// Rectangle - subclass 构造器
function Rectangle() {
Shape.call(this); // call super constructor.
}
// subclass extends superclass 原型
Rectangle.prototype = Object.create(Shape.prototype);
//If you don't set Rectangle.prototype.constructor to Rectangle,
//it will take the prototype.constructor of Shape (parent).
//To avoid that, we set the prototype.constructor to Rectangle (child).
Rectangle.prototype.constructor = Rectangle;
const rect = new Rectangle();
console.log('Is rect an instance of Rectangle?', rect instanceof Rectangle); // true
console.log('Is rect an instance of Shape?', rect instanceof Shape); // true
rect.move(1, 1); // Outputs, 'Shape moved.'// Shape - 父类
function Shape() {
this.x = 0;
this.y = 0;
}
// 父类方法
Shape.prototype.move = function(x, y) {
this.x += x;
this.y += y;
console.info('Shape moved.');
};
// Rectangle - subclass 构造器
function Rectangle() {
Shape.call(this); // call super constructor.
}
// subclass extends superclass 原型
Rectangle.prototype = Object.create(Shape.prototype);
//If you don't set Rectangle.prototype.constructor to Rectangle,
//it will take the prototype.constructor of Shape (parent).
//To avoid that, we set the prototype.constructor to Rectangle (child).
Rectangle.prototype.constructor = Rectangle;
const rect = new Rectangle();
console.log('Is rect an instance of Rectangle?', rect instanceof Rectangle); // true
console.log('Is rect an instance of Shape?', rect instanceof Shape); // true
rect.move(1, 1); // Outputs, 'Shape moved.'Object.create()、new Object()和{}的区别 - 掘金
Object.create() - JavaScript | MDN
Object.create() 详解_bug收集的博客-CSDN博客_object.create