淺拷貝

淺拷貝只拷貝一層，深層次的對象只拷貝引用

var obj = {
    name: 'zhangsan',
    age: 18,
    omg: {
        name: 'omg'
    }
}

var ob = {};
for (var i in obj) {
    ob[i] = obj[i]
}

console.log(ob);

拷貝對象ob

ob深層對象omg改變會改變原始對象obj中的omg

var obj = {
    name: 'zhangsan',
    age: 18,
    omg: {
        name: 'omg'
    }
}

var ob = {};
for (var i in obj) {
    ob[i] = obj[i]
}
ob.omg.name = 'ob';
ob.name = 'omg';
console.log(ob)
console.log(obj);

淺拷貝會改變深層對象

ES6 新增的淺拷貝方法 Object.assign

var obj = {
    name: 'zhangsan',
    age: 18,
    omg: {
        name: 'omg'
    }
}

var ob = {};
Object.assign(ob,obj);

console.log(ob)

對象淺拷貝方法assign

利用遞歸進行對象的深拷貝

var obj = {
    name: 'zhangsan',
    age: 18,
    omg: {
        name: 'omg'
    },
    yy: [1,2,3]
}

var ob = {};
function deepCopy(newO,oldO) {
    for (var k in oldO) {
        var item = oldO[k];
        if (item instanceof Array) {
            newO[k] = [];
            deepCopy(newO[k],item);
        } else if (item instanceof Object) {
            newO[k] = {};
            deepCopy(newO[k],item);
        } else {
            newO[k] = item;
        }
    }
}

deepCopy(ob,obj);
ob.omg.name = 'ccc';
ob.yy.push(1,2);
console.log(ob);
console.log(obj);

深拷貝