js splice


```type(start, deleteCount, ...insertitems)```


js insert
> [Array.prototype.splice()](https://developer.mozilla.org/ko/docs/Web/JavaScript/Reference/Global_Objects/Array/splice)

> [[JS/Array] slice()와 splice()의 차이점](https://im-developer.tistory.com/103)

> [How to insert an item into an array at a specific index (JavaScript)?](https://stackoverflow.com/questions/586182/how-to-insert-an-item-into-an-array-at-a-specific-index-javascript)

