js 深拷贝

/**
 * 深拷贝
 */
function deepCopy(target){ 
    let copyed_objs = [];// 此数组解决了循环引用和相同引用的问题，它存放已经递归到的目标对象 
    function _deepCopy(target){ 
        if((typeof target !== 'object')||!target){return target;}
        for(let i= 0 ;i<copyed_objs.length;i++){
            if(copyed_objs[i].target === target){
                return copyed_objs[i].copyTarget;
            }
        }
        let obj = {};
        if(Array.isArray(target)){
            obj = [];// 处理target是数组的情况 
        }
        copyed_objs.push({target:target,copyTarget:obj}) 
        Object.keys(target).forEach(key=>{ 
            if(obj[key]){ return;} 
            obj[key] = _deepCopy(target[key]);
        }); 
        return obj;
    } 
    return _deepCopy(target);
}