Bookmarklet for assisting buy and sell decisions in coins.ph

cph-bookmarklet.js

/*  Copyright 2017 Vicente de Rivera III
 
     This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/*
Bookmarklet for coins.ph to assist in revealing important details about it's Buy and Sell prices.
To generate the bookmarklet:
1. Go to http://bookmarklets.org/maker/
2. Paste this code.
3. Drag n drop the link found in the bottom.
*/

var quotes = document.getElementsByClassName('quotes')[0];

var buyStr = quotes.children[0].innerText.split(" ")[1].replace(",","");
var buy = parseInt(buyStr);

var sellStr = quotes.children[2].innerText.split(" ")[1].replace(",","");
var sell = parseInt(sellStr);

var diff = buy - sell
var diffStr = "Difference: " + diff + " PHP";

var spread = (buy - sell) / sell;
var spreadStr = "Spread: " + (spread * 100).toFixed(2) + " %";

/*var breakEven = diff / buy;
var breakEvenStr = "To break even, you need BTC to go up " + (breakEven * 100).toFixed(2) + " %";*/

var breakEvenStr = "Remember to only sell at price " + buyStr + " PHP or higher."

quotes.appendChild(document.createTextNode(" ---> "));
quotes.appendChild(document.createTextNode(diffStr));

quotes.appendChild(document.createTextNode(" ---> "));
quotes.appendChild(document.createTextNode(spreadStr));

quotes.appendChild(document.createTextNode(" ---> "));
quotes.appendChild(document.createTextNode(breakEvenStr));

/*EXPERIMENT calling Gemini*/

function processRequest(e) {
    if (xhr.readyState == 4 && xhr.status == 200) {
        var response = JSON.parse(xhr.responseText);
        var geminiUSD = response.USD;
        /* assume 1 USD = 50 PHP */
        var geminiPHP = (response.USD * 50).toFixed(2);
        var geminiPHPStr = geminiPHP + " PHP";
        var geminiCPHpercentDiff = (buy - geminiPHP) / geminiPHP;
        var geminiCPHpercentDiffStr = (geminiCPHpercentDiff * 100).toFixed(2) + " %";

        quotes.appendChild(document.createTextNode(" --> "));
        quotes.appendChild(document.createTextNode("Gemini: " + geminiPHPStr));
        quotes.appendChild(document.createTextNode(" --> "));
        quotes.appendChild(document.createTextNode("Gemini/CPH % Diff: " + geminiCPHpercentDiffStr));
    }
}

var xhr = new XMLHttpRequest();
xhr.open('GET', "https://min-api.cryptocompare.com/data/price?fsym=BTC&tsyms=USD&e=Gemini", true);
xhr.onreadystatechange = processRequest;
xhr.send();