> For example, the last item in an array: arr[arr.length - 1] Of course, one could argue that this just means that the length of an array is a less meanin

> For example, the last item in an array: arr[arr.length - 1] Of course, one could argue that this just means that the length of an array is a less meaningful property than its last populated index (what Perl calls `$#array`); one can imagine arr[arr.lastIndex] or, which is probably better, just arr.last > Or a found item by index number: if (arr.indexOf("thing") > -1) { This comes from overloading return values to communicate errors. It's not clear to me that if (arr.indexOf("thing") > 0) { (in a hypothetical analogue with 1-indexed lists) demonstrates any clear improvement; something like if (arr.member?("thing")) { seems preferable in terms of clarity (ignoring the efficiency objection that one would probably immediately after look for the index).