js对象操作常用方法

一、创建对象

1.字面量创建

//字面量创建
let obj = {a:1}

2.构造函数创建

//构造函数创建
function Person(name,age){
    this.name = name;
    this.age = age;
}
let person = new Person('Bob',12);

二、访问对象属性

1.点符号

let obj = {a:1}
obj.a

2.方括号

let obj = {a:1}

obj['a']    //1

三、添加属性

obj.c = 3;
obj['d'] = 4;

四、删除属性

delete obj.a

五、判断属性是否存在

1.in运算符

let obj = {a:1,b:2}

'a' in obj    //true

2.hasOwnProperty方法

obj.hasOwnProperty('a'); // true

六、遍历对象属性

1.for...in...循环

for (let prop in obj) {
    if (obj.hasOwnProperty(prop)) {
        console.log(`Key: ${prop}, Value: ${obj[prop]}`);
    }
}

2.Object.keys，Object.values，Object.entries

Object.keys(obj).forEach(key => console.log(key));
Object.values(obj).forEach(value => console.log(value));
Object.entries(obj).forEach(([key, value]) => console.log(`${key}: ${value}`));

七、深拷贝与浅拷贝

1.浅拷贝

let obj = {a:1}
let shallowCopy = Object.assign({},obj)

2.深拷贝

let obj = {a:1}
let deepCopy = JSON.parse(JSON.stringify(obj))

八、合并对象

Object.assign

let obj2 = { e: 5 };
let merged = Object.assign({}, obj, obj2);

九、其他方法

1.Object.is() 比较两个值是否严格相等

Object.is(obj, obj); // true

2.Object.defineProperty() 定义或修改属性，并返回该对象

let obj = {}
Object.defineProperty(obj, 'f', { value: 6, writable: true, enumerable: true, configurable: true });
console.log(obj)    //{f:6}