Js USES the array length property to empty and truncate arrays

1. Empty the array with length:

<script>
    var arr1 = ['aaa','bbbb','//www.jb51.net'];
    alert(arr1);
    arr1.length = 0;
    alert(arr1); //The array is empty
</script>

2. Truncate an array with length:

<script>
    var arr1 = ['aaa','bbbb','c','d','e'];
    arr1.length = 3;
    alert(arr1); //Truncate the array aaa, BBBB,c
</script>