深拷贝的原理
1.先进行 类型判断
if(obj==null) return obj; if(obj instanceof RegExp) return new RegExp(obj); if(obj instanceof Date) return new Date(obj); //... if(typeof obj !== 'object') return obj;
2. 判断是 数组还是 对象
let instance = new obj.constructor;
demo
function deepClone(obj,hash=new WeakMap()) { if(obj==null) return obj; if(obj instanceof RegExp) return new RegExp(obj); if(obj instanceof Date) return new Date(obj); //... if(typeof obj !== 'object') return obj; let instance = new obj.constructor; // if(hash.has(obj)) return hash.get(obj); // hash.set(obj,instance); // for (const key in obj) { // if (obj.hasOwnProperty(key)) { // instance[key] =deepClone(obj[key],hash); // } // } return instance; } console.log(deepClone({a:1,b:2,c:{c:1}})); console.log(deepClone([1,2,3,4]));
输出 :
{}
[]
3. 遍历数组或者数组 利用 for ..... in
4. 进行拷贝
for (const key in obj) { if (obj.hasOwnProperty(key)) { instance[key] =deepClone(obj[key],hash); } }
5.
if(hash.has(obj)) return hash.get(obj); hash.set(obj,instance);
这里是先判断 是否有被拷贝了 如果被拷贝了 就返回 它
设置映射
完整demo :
function deepClone(obj,hash=new WeakMap()) { if(obj==null) return obj; if(obj instanceof RegExp) return new RegExp(obj); if(obj instanceof Date) return new Date(obj); //... if(typeof obj !== 'object') return obj; let instance = new obj.constructor; if(hash.has(obj)) return hash.get(obj); hash.set(obj,instance); for (const key in obj) { if (obj.hasOwnProperty(key)) { instance[key] =deepClone(obj[key],hash); } } return instance; } console.log(deepClone({a:1,b:2,c:{c:1}})); console.log(deepClone([1,2,3,4]));
输出 :
{ a: 1, b: 2, c: { c: 1 } }
[ 1, 2, 3, 4 ]
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