js对象的浅拷贝与深拷贝

// 浅拷贝
const shallow = {a: 1};
const new11 = shallow;
const new22 = {};
Object.assign(new22, shallow);

// 深拷贝
function deepClone(obj) {
    if (obj === null || typeof obj !== 'object') return obj;
    var result = Array.isArray(obj) ? [] : {};

    // 拷贝Symbols
    const sym = Object.getOwnPropertySymbols(obj);
    sym.forEach(function (item) {
        if (Object.prototype.toString.call(obj[item]) === '[object Object]') {
            result[item] = deepClone(obj[item]);
        } else {
            result[item] = obj[item];
        }
    });

    // 拷贝其他值
    for (var key in obj) {
        if (Object.prototype.toString.call(obj[key]) === '[object Object]') {
            result[key] = deepClone(obj[key]);
        } else {
            result[key] = obj[key];
        }
    }

    return result;
}

const complexObj = {
    a: 'string',
    b: 0,
    c: true,
    d: null,
    e: undefined,
    f: Symbol(),
    g: {
        aa: 'test',
        bb: function() {
            console.log('inner');
        }
    },
    h: function() {
        console.log('outer');
    },
    i: [1, 2, 3, 4, 5]
};
const new1 = JSON.parse(JSON.stringify(complexObj)); // JSON方法的深拷贝，有缺陷
const new2 = deepClone(complexObj);
// 修改数据
complexObj.b = 123; // 第一层
complexObj.g.aa = 'abc'; // 对象第二层
console.log(complexObj);
console.log(new1);
console.log(new2);