Comments (2)
深复制实现
主要考察的是递归、数组和对象的存储。
1. 使用 for ... in
的形式
function deepClone(obj) {
// 注意点:深复制这里应该是[...obj] : {...obj} 而不应该是 [] : {} ,为什么呢?
var result = Array.isArray(obj) ? [...obj] : {...obj} ;
for (var key in obj) {
if (obj.hasOwnProperty(key)) {
if (typeof obj[key] === 'object' && obj[key]!==null) {
result[key] = deepClone(obj[key]);
} else {
result[key] = obj[key];
}
}
}
return result;
}
2. 使用 Reflect.ownKeys 的方式
function deepClone(obj) {
function isObject(o) {
return (typeof o === 'object' || typeof o === 'function') && o !== null
}
if (!isObject(obj)) {
throw new Error('非对象')
}
let isArray = Array.isArray(obj)
let newObj = isArray ? [...obj] : { ...obj }
Reflect.ownKeys(newObj).forEach(key => {
newObj[key] = isObject(obj[key]) ? deepClone(obj[key]) : obj[key]
})
return newObj
}
使用 JSON.parse/JSON.stringify
的形式
function deepClone(arr){
return JSON.parse(JSON.stringify(arr))
}
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对于上面说的
注意点:深复制这里应该是[...obj] : {...obj} 而不应该是 [] : {}
这一句还是没太明白,使用 [] : {}
来测试还是能够实现深复制啊
function deepClone(obj) {
// 注意点:深复制这里应该是[...obj] : {...obj} 而不应该是 [] : {} ,为什么呢?
let result = Array.isArray(obj) ? [] : {};
// var result = Array.isArray(obj) ? [...obj] : {...obj} ;
for (let key in obj) {
if (obj.hasOwnProperty(key)) {
if (typeof obj[key] === 'object' && obj[key] !== null) {
result[key] = deepClone(obj[key]);
} else {
result[key] = obj[key];
}
}
}
return result;
}
let obj = {
a: 1,
b: {b1: 1, b2: 2},
c: [1, 2],
d: function() {}
};
let res = deepClone(obj);
console.log(res.b === obj.d) // false
console.log(res) // obj 的全部复制了
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