An ES2015 spec-compliant Array.prototype.indexof 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.indexOf depends on a receiver (the “this” value), the main export takes the array to operate on as the first argument.
var indexOf = require('array.prototype.indexof');
var assert = require('assert');
assert.equal(indexOf([1, 2, 3], 2), 1);
assert.equal(indexOf([1, 0, 1], 1), 0);
assert.equal(indexOf([1, 2, 3], 4), -1);
assert.equal(indexOf([NaN], NaN), -1);var indexOf = require('array.prototype.indexof');
var assert = require('assert');
/* when Array#indexOf is not present */
delete Array.prototype.indexOf;
var shimmedMap = indexOf.shim();
assert.equal(shimmedMap, indexOf.getPolyfill());
assert.equal([1, 2, 3].indexOf(2), 1);
assert.equal([1, 0, 1].indexOf(1), 0);
assert.equal([1, 2, 3].indexOf(4), -1);
assert.equal([NaN].indexOf(NaN), -1);var indexOf = require('array.prototype.indexof');
var assert = require('assert');
/* when Array#indexOf is present */
var shimmedMap = indexOf.shim();
assert.equal(shimmedMap, Array.prototype.indexOf);
assert.equal([1, 2, 3].indexOf(2), 1);Simply clone the repo, npm install, and run npm test