A Greasemonkey script with a "whitelist" of keywords

search_redirector.js

// ==UserScript==
// @name         Search redirector
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       Anderson Green
// @match      *://*/*
// @grant        none
// ==/UserScript==

//alert(window.location.href);
//var topics = "datalog|earley parser|minizinc|satisfiability modulo|logic programming|differential equations|integration by parts|parser generator|polynomial long division|disjunctive normal form|conjunctive normal form".split("|");

var topics = "linear algebra|dot product|linear independence|basis vector|Gaussian elimination|differential equations|trigonmetric identities|related rates|separable differential equations|polynomial long division|integration by parts|synthetic division|polar coordinates|double angle formula|exact differential equations".split("|");

//var hours = Math.abs(Date.parse('01 Jan 1970 00:00:00 GMT') - (new Date()))*1000.0 / 36e5;

var topic = topics[Math.floor(Math.random() * topics.length)];
//alert(Math.floor(hours % topics.length));

//alert(topic);


var oldURL = document.referrer;
//alert(oldURL);
var to_match = new RegExp(topics.join("|"), "i");
//var to_match = /logic programming|smt-lib/i;
var url = window.location.toString();
var search_term = topic.replace(" ","+");


if(url.indexOf("www\.google\.com\/search") !== -1 && url.indexOf("q\=") !== -1 && !(to_match.test (document.body.innerHTML)) && (url.indexOf("www.google.com/search?q=") !== -1) && !(/ogs\.google\.com|google\.com\/sorry/i.test (window.location.href))){
    window.location = url.replace(/q\=/, 'q="'+search_term+'" ');
    //alert(to_match);
}
else if (!(to_match.test (document.body.innerHTML) ) && !(/ogs\.google\.com|google\.com\/sorry|www\.google\.com\/search\?q\=/i.test (window.location.href))){
    //alert(to_match);
    //alert(window.location.href);
    window.history.go(-1);
}