JavaScript深拷贝和浅拷贝的常用方法

浅拷贝

方法一

function shallowClone(obj1, obj2) {
    let obj = obj2 || {}
    for (let i in obj1) {
        obj[i] = obj1[i];
    }
    return obj;
}
    let obj = { a: {b: "hello", c: 21} };
    let obj2 = shallowClone(obj,{d:33});
    obj.a.b = 'world';
    console.log(obj2);

方法二

 let obj = { a: {b: "hello", c: 21} };
 let obj2 = Object.assign({}, obj);
 obj.a.b = 'world'
 console.log(obj2);

深拷贝

方法一

function deepClone(initalObj, finalObj) {
    let obj = finalObj || {}
    for (let i in initalObj) {
        let prop = initalObj[i];
        if (prop == obj) {//防止循环引用
            continue;
        }
        if (typeof prop === 'object') {
            obj[i] = (prop.constructor === Array)?[]:{};
            deepClone(prop, obj[i]);
        } else {
            obj[i] = prop; 
        }
    }
    return obj;
}
let obj = { a: {b: "hello", c: 21} };
let obj2 = deepClone(obj,{d:33});
obj.a.b = 'world';
console.log(obj2);

方法二

 let obj = { a: {b: "hello", c: 21} };
 let obj2 = JSON.parse(JSON.stringify(obj));
 obj.a.b = 'world';
 console.log(obj2);
 //只有可以转成JSON格式的对象才可以这样用，JSON不支持undefined和function的拷贝