> For the complete documentation index, see [llms.txt](https://april.gitbook.io/learning-js/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://april.gitbook.io/learning-js/chapter-4./4.3/4.3.4.md).

# 4.3.4 배열을 수정할 때 감소하는 인덱스 사용하기

인덱스를 배열 사이즈-1로 잡고 줄여나감

```javascript
for (let i=bigArrayOfNumbers.length-1; i>=0; i--) {
    if (isPrime(bigArrayOfNumbers[i]))
        bigArrayOfNumbers.splice(i, 1);
}
```