auto advance instagram on a timer

auto-advance.js

// ==UserScript==
// @name         InstaAutoAdvance
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Automatically advance instagram photos on a timer
// @author       You
// @match        https://www.instagram.com/*
// @grant        none
// ==/UserScript==

// Type 'niko' to start the script and 'okin' to stop it.

(function() {
	"use strict";

	var startKeyword = "niko";
	var endKeyword = reverse(startKeyword);
	var codes = {};
	for (var i=0; i < 26; i++) {
		codes[String.fromCharCode(97+i)] = 97+i;
	}

	var minutes = 10;
	var interval = 1000 * 60 * minutes;
	var matched = 0;

	var id = 0;
	document.addEventListener("keypress", function(input) {
		// If the id of the interval is set then it should probably stop
		if (id != 0) {
			if (input.keyCode === codes[endKeyword[matched]]) {
				matched++;
			} else {
				matched = 0;
			}
			if (matched == startKeyword.length) {
				clearInterval(id);
				id = 0;
				matched = 0;
			}
		} else {
			if (input.keyCode === codes[startKeyword[matched]]) {
				matched++;
			} else {
				matched = 0;
			}
			if (matched == startKeyword.length) {
				id = setInterval(function(){
					document.getElementsByClassName("coreSpriteRightPaginationArrow")[0].click();
				}, interval);
				matched = 0;
			}
		}
	});
})();

function reverse(s){
	return s.split("").reverse().join("");
}