Question

It looks like the original functionality of Array.lastIndexOf was what I’m looking for, but it was changed. Any idea how to replicate the old functionality?

http://blog.sugarjs.com/post/8452749291/v0-9-2-indexof-lastindexof-fixed

Answer 1

After looking at the sugar.js docs, it appears that Array#findIndex does the reverse of what I’m trying to do, so here’s my solution which uses that:

Array.prototype.findLastIndex = function(f, startIndex, loop) {
    var reverseIndex = this.clone().reverse().findIndex(f, startIndex, loop);
    if (reverseIndex < 0) {
        return reverseIndex;
    }
    return this.length - reverseIndex - 1;
};