When finished, this Tampermonkey/Greasemonkey script should be able to convert any page from Dogecoins to USD

doge-usd.js

// ==UserScript==
// @name       doge-usd
// @namespace  
// @version    2014.03.16
// @description converts pages wit dogecoin 2 USD. 4 u/thatmudkipguy. so birthday. much happy.
// @include *
// @grant GM_xmlhttpRequest
// @grant GM_log
// @grant GM_setValue
// @grant GM_getValue
// @copyright goatandsheep
// ==/UserScript==

// if u want the Ɖ

/*  This will get the initial value of the exchange rate-it's faster if you just send one request,
    then use the value for the rest*/
function loadXMLDoc (urlAPI){
    var xmlhttp=new XMLHttpRequest();
    var txt;
    xmlhttp.onreadystatechange=function()
    {
        if (xmlhttp.readyState==4 && xmlhttp.status==200)
        {
            txt = xmlhttp.responseText;
            txt = eval ("(" + txt + ")");
            txt = txt.data.amount;
            GM_log(txt);
            GM_setValue('exchangeRate', txt);
            console.log("bob begins");
            return
        }
    }
    xmlhttp.open("GET", urlAPI,true);
    xmlhttp.send();
}

function woofRequest(shibe) {
    for(i in shibe){
        shibe[i] = shibe[i];
        console.log(shibe[i]);
        shibe[i] = shibe[i].replace(/\Ɖ|ᴆ| |,/g, '');                               // remove commas and Ɖoge lettering
        // so metric
        // much extra inputs:
        // ###k, ###K, ###M, ###T, ###G
        var multiplier = 1.0;                                                   // for the value of kilo, mega, and other metric prefixes
        var coinz = parseFloat(shibe[i]);
        var letter = shibe[i].substring((coinz.toString()).length, (shibe[i].length));// take the letter at the end

        if ((letter === 'k') || (letter === 'K')) {multiplier = 1000.0; }       // kilo
        else if (letter === 'M') {multiplier = 1000000.0; }                     // mega
        else if (letter === 'G') {multiplier = 1000000000.0; }                  // giga
        else if (letter === 'T') {multiplier = 1000000000000.0; }               // tera
        coinz = coinz * multiplier;
        console.log("coinz: " + coinz);
        shibe[i] = coinz * GM_getValue('exchangeRate');

        shibe[i] = (Math.round(shibe[i] * 100)) / 100;
        shibe[i] = '$' + shibe[i].toString();
        console.log("This is " + i.toString());
        console.log(shibe[i]);
    }
    return shibe;
}

/** if u got sumthn 2 convert, m8, il teece u 2 use diffrent currencies, so u better reed how 2 change 2 a diffrent API
*   if ur changin the url, check the parsin of the api and change the onload section rite
*   info 4 dogeapi: https://www.dogeapi.com/api_documentation
*   sample 4 u blokes:
*   url: https://www.dogeapi.com/wow/v2/?a=get_current_price&convert_to=USD&amount_doge=1000
*   response: {"data":{"amount":0.00133}}
*
*   P.S. dogeapi cud convert 2:
*       * "USD"
*       * "BTC"
**/

loadXMLDoc('https://www.dogeapi.com/wow/v2/?a=get_current_price&convert_to=USD&amount_doge=1');
console.log(GM_getValue('exchangeRate'));

// so modified
// OP very noob
// sauce: http://www.techradar.com/news/internet/the-beginner-s-guide-to-greasemonkey-scripting-598247/4#articleContent

var textNodes = document.evaluate("//text()", document, null, XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE, null);

var searchRE;

// add more urls here, sorry for the difficulty due to need to use regular expressions
// check your regex here: https://www.debuggex.com/#cheatsheet
/** if that is too difficult, put this:
*   if ((document.location.href).substring(0,'%url%'.length)==='%url%')
**/
//  sample: 'http://www.reddit.com/r/dogemarket/comments/20k26i/sg_tf2_key_for_2400_doge/'.match(/((http|https):\/\/+(www\.reddit.com\/r\/dogemarket))?/)
if ((document.location.href).match(/((http|https):\/\/(www\.reddit\.com\/r\/dogemarket))/)) {
    //  same as below, but added capability for metric inputs: #k/K/M/T/G
    searchRE = /(Ɖ([1-9]{1}\d{0,2})(,? ?\d{3})*(\.\d*)?)|(([1-9]{1}\d{0,2})(,? ?\d{3})*(\.\d*)?( doge| DOGE))|(([1-9]{1}\d{0,2})(,? ?\d{3})*(\.\d*)?ᴆ)|(([1-9]{1}\d{0,2})(,? ?\d{3})*(\.\d*)?([KMGT]|[k]))/gi;
}
else {
/** much inputs:
*   #,###,###.# doge
*   # DOGE
*   Ɖ#
*   #ᴆ
**/
    searchRE = /(Ɖ([1-9]{1}\d{0,2})(,? ?\d{3})*(\.\d*)?)|(([1-9]{1}\d{0,2})(,? ?\d{3})*(\.\d*)?( doge| DOGE))|(([1-9]{1}\d{0,2})(,? ?\d{3})*(\.\d*)?ᴆ)/gi;
}
var i;
// find and replace
for (i = 0; i < textNodes.snapshotLength; i++) {
    var node = textNodes.snapshotItem(i);
    if (node.data.match(searchRE)){
        console.log(node.data.match(searchRE));
        node.data = node.data.replace(searchRE, woofRequest(node.data.match(searchRE)));
    }
}

One of the problems is that the regex for Reddit is catching lowercase letters, resulting in many extra inputs even though I checked using the regex checker. Other than that, I don't know what's wrong.

allows for spaces every 3 digits