In the following demo only script, I clear (reset) the "tarr" two different ways.
My questions are:
1. Is one way better than the other? More acceptable? Or are they both the same?
2. Is there a concern with "memory leakage" using either method?

Code:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />

<title> Clear Array Contents </title>

</head>
<body>
<button onclick="initArr(arr1)">Initial Array (1..5)</button>
<button onclick="initArr(arr2)">Initial Array (5..1)</button>
<button onclick="initArr(arr1.concat(arr2))">concat Arrays</button>

<p>
<!-- <button onclick="showArr(tarr)">Show tarray</button> -->

<button onclick="clearArr1(tarr)">Clear []</button>
<button onclick="clearArr2(tarr)">Clear =0</button>
<p>
<div id="debug"></div>

<script type="text/javascript">
var arr1 = [1,2,3,4,5];
var arr2 = [5,4,3,2,1];

var tarr = [];  // global array

function initArr(arr) { tarr = arr.slice(0);  showArr(tarr); }
function showArr(arr) { document.getElementById('debug').innerHTML = arr; }

function clearArr1(arr) { tarr = [];  showArr(tarr); }
function clearArr2(arr) { tarr.length = 0;  showArr(tarr); }

</script>

</body>
</html>