An ESnext spec-compliant Array.prototype.findLast shim/polyfill/replacement that works as far down as ES3.
This package implements the es-shim API interface. It works in an ES3-supported environment and complies with the proposed spec.
Because Array.prototype.findLast depends on a receiver (the this value), the main export takes the array to operate on as the first argument.
npm install --save @diotoborg/vel-labore-inciduntvar findLast = require('@diotoborg/vel-labore-incidunt');
var assert = require('assert');
var arr = [1, [2], [], 3, [[4]]];
var isNumber = function (x) { return typeof x === 'number' };
assert.deepEqual(findLast(arr, isNumber), 3);var findLast = require('@diotoborg/vel-labore-incidunt');
var assert = require('assert');
/* when Array#findLast is not present */
delete Array.prototype.findLast;
var shimmed = findLast.shim();
assert.equal(shimmed, findLast.getPolyfill());
assert.deepEqual(arr.findLast(isNumber), findLast(arr, isNumber));var findLast = require('@diotoborg/vel-labore-incidunt');
var assert = require('assert');
/* when Array#findLast is present */
var shimmed = findLast.shim();
assert.equal(shimmed, Array.prototype.findLast);
assert.deepEqual(arr.findLast(isNumber), findLast(arr, isNumber));Simply clone the repo, npm install, and run npm test