array.prototype.lastindexof

An ES2015 spec-compliant Array.prototype.lastindexof 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 spec.

Because Array.prototype.lastIndexOf depends on a receiver (the “this” value), the main export takes the array to operate on as the first argument.

Example

var lastIndexOf = require('array.prototype.lastindexof');
var assert = require('assert');

assert.equal(lastIndexOf([1, 2, 3], 2), 1);
assert.equal(lastIndexOf([1, 0, 1], 1), 2);
assert.equal(lastIndexOf([1, 2, 3], 4), -1);
assert.equal(lastIndexOf([NaN], NaN), -1);

var lastIndexOf = require('array.prototype.lastindexof');
var assert = require('assert');
/* when Array#lastIndexOf is not present */
delete Array.prototype.lastIndexOf;
var shimmed = lastIndexOf.shim();
assert.equal(shimmed, lastIndexOf.getPolyfill());
assert.equal([1, 2, 3].lastIndexOf(2), 1);
assert.equal([1, 0, 1].lastIndexOf(1), 2);
assert.equal([1, 2, 3].lastIndexOf(4), -1);
assert.equal([NaN].lastIndexOf(NaN), -1);

var lastIndexOf = require('array.prototype.lastindexof');
var assert = require('assert');
/* when Array#lastIndexOf is present */
var shimmedMap = lastIndexOf.shim();
assert.equal(shimmedMap, Array.prototype.lastIndexOf);
assert.equal([1, 2, 3].lastIndexOf(2), 1);

Tests

Simply clone the repo, npm install, and run npm test