Answer 1

Array.prototype.mySplice = function(start, deleteCount, ...items) {
        const preLen = this.length + items.length
        const rightArr = items.concat(this.slice(start + deleteCount))
        let i = start
        while(rightArr.length) {
          this[i] = rightArr.shift()
          i++
        }
        this.length = preLen - deleteCount
      }

最短代码数

Answer 2

大佬深拷贝没考虑环么？

Answer 3

楼主的深复制方法只支持json对象，并不完美啊。可以参考http://jerryzou.com/posts/dive-into-deep-clone-in-javascript/