对象
(1)对象字面量
const age = 12; const name = "Amy"; const person = {age, name}; console.log(person); //{age: 12, name: "Amy"}
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方法也可以简写:
const person = { sayHi(){ console.log("Hi"); } } person.sayHi(); //"Hi"
const obj = { ["he"+"llo"](){ return "Hi"; } } obj.hello(); //"Hi"
注意点:属性的简洁表示法和属性名表达式不能同时使用,否则会报错。
const hello = "Hello"; const obj = { [hello] }; console.log(obj); //SyntaxError: Unexpected token } const hello = "Hello"; const obj = { [hello+"2"]:"world" }; console.log(obj); //{Hello2: "world"}
(2)对象的扩展运算符
拓展运算符(...)用于取出参数对象所有可遍历属性然后拷贝到当前对象。
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基本用法
let person = {name: "Amy", age: 15}; let someone = { ...person }; console.log(someone); //{name: "Amy", age: 15}
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可用于合并两个对象
let age = {age: 15}; let name = {name: "Amy"}; let person = {...age, ...name}; console.log(person); //{age: 15, name: "Amy"}
let person = {name: "Amy", age: 15}; let someone = { ...person, name: "Mike", age: 17}; console.log(someone); //{name: "Mike", age: 17}
let person = {name: "Amy", age: 15}; let someone = {name: "Mike", age: 17, ...person}; console.log(someone); //{name: "Amy", age: 15}
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拓展运算符后面是空对象,没有任何效果也不会报错。
let a = {...{}, a: 1, b: 2}; console.log(a); //{a: 1, b: 2}
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拓展运算符后面是null或者undefined,没有效果也不会报错。
let b = {...null, ...undefined, a: 1, b: 2}; console.log(b); //{a: 1, b: 2}
(3)对象的新方法
Object.is(value1, value2):用来比较两个值是否严格相等,与(===)基本类似。
Object.is("q","q"); // true Object.is(1,1); // true Object.is([1],[1]); // false Object.is({q:1},{q:1}); // false
与===的区别
//一是+0不等于-0 Object.is(+0,-0); //false +0 === -0 //true //二是NaN等于本身 Object.is(NaN,NaN); //true NaN === NaN //false