Steam Community Market Sales Script

// ==UserScript==
// @name         Steam Market History Button
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  Adds a button below steam market price graphs to open the sale json.
// @author       jh34ghu43gu
// @match        https://steamcommunity.com/market/listings/440/*
// @icon         data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==
// @require      http://code.jquery.com/jquery-latest.js
// @require      https://gist.github.com/raw/2625891/waitForKeyElements.js
// @grant        GM_getValue
// ==/UserScript==

console.log("History Button Script Active");

var urlStart = "https://steamcommunity.com/market/pricehistory/?appid=440&market_hash_name=";

waitForKeyElements(".jqplot-target", addButton);

function addButton(jNode) {
    console.log(urlStart + document.getElementsByClassName("market_listing_nav")[0].childElements()[1].innerText);
    var button = document.createElement("a");
    button.href = urlStart + document.getElementsByClassName("market_listing_nav")[0].childElements()[1].innerText;
    button.id = "pricehistory_button";
    button.innerText = "Price History JSON";
    jNode[0].parentNode.insertBefore(document.createElement("br"), jNode[0]);
    jNode[0].parentNode.insertBefore(button, jNode[0]);
}