user.js

// ==UserScript==
// @name         Estately + Zillow Plugin
// @namespace    http://tampermonkey.net/
// @version      0.1.1
// @description  Plugin
// @author       You
// @match        https://www.estately.com/*
// @grant        none
// @run-at      document-end
// @require https://code.jquery.com/jquery-3.3.1.min.js
// ==/UserScript==

function run() {
    'use strict';
    const Http = new XMLHttpRequest();
    var parser = new DOMParser();
    var houses = JSON.parse(xpath("/html/head/script[14]").innerText)["@graph"];
    var provider = "https://api.allorigins.ml/get?url=";
    let markers = document.querySelectorAll(".map-marker");
    var labels = document.querySelectorAll(".result-item");
    var numHouses = houses.length;
    var styleText = "";
    if (markers.length != labels.length) {
        numHouses = 0;
        alert(`the # of markers is ${markers.length} and the # of houses listed is ${houses.length}. ERROR`);
    }
    console.log("houses received by DATA:",houses.length / 2);
    for (var i=0; i<numHouses; i+=2) {
        var house = houses[i].address;
        var adjustedIndex = Math.floor(i / 2);
        var houseMarker = markers[adjustedIndex];
        var houseLabel = labels[adjustedIndex];
        console.log(adjustedIndex,houseMarker,houseLabel);
        var price = parseFloat(houses[i+1].offers.price);
        var uri = `zws-id=X1-ZWz1fvm3ocr9jf_4rdd9&address=${house.streetAddress}&citystatezip=${house.postalCode}`;
        var url = "https://www.zillow.com/webservice/GetDeepSearchResults.htm?" + uri;
        console.log("Price:" + price);
        styleText += modifyHouseOnPage(houseMarker, houseLabel, url, price)



    }


};
function addStyle(styleText) {
    console.log("Style:" + styleText);
    var head = document.head || document.getElementsByTagName('head')[0], style = document.createElement('style');
    style = document.createElement('style');

    style.type = 'text/css';
    if (style.styleSheet){
         style.styleSheet.cssText = styleText;
    } else {
         style.appendChild(document.createTextNode(styleText));
    }
    head.appendChild(style);
}
function modifyHouseOnPage(houseMarker, houseLabel, url, price) {
    let goodThreshold = 72;
    let greatThreshold = 60;
    let uniqueLabelTag = houseLabel.classList[3]
    var style = "";
            $.getJSON('https://api.allorigins.ml/get?url=' + encodeURIComponent(url) + '&callback=?', function(data){
            let zpid = data.contents.split("<zpid>",-1)[1].split("</zpid>",-1)[0];
            let url = data.contents.split("<homedetails>",-1)[1].split("</homedetails>",-1)[0];
            console.log("ZPID:" + zpid);
            console.log("URL:" + url);
            if (zpid != undefined) {
                var zestURL = `https://www.zillow.com/webservice/GetZestimate.htm?zws-id=X1-ZWz1fvm3ocr9jf_4rdd9&zpid=${zpid}&rentzestimate=true`
                console.log(zestURL);
                $.getJSON('https://api.allorigins.ml/get?url=' + encodeURIComponent(zestURL) + '&callback=?', function(data){
                    let zestimate = data.contents.split("<rentzestimate>",-1)[1].split("</amount>",-1)[0].replace("<amount currency=\"USD\">","",-1);
                    console.log("zestimate:" + zestimate);
                    let content = `<a href="${url}">${zestimate}</a>`
                    let score = price / zestimate;
                    console.log("score:" + score);
                    var color = ""
                    // 10000 / 500 = 20
                    if (score < greatThreshold) {
                        color = "green";
                    } else if (score < goodThreshold) {
                        color = "yellow";
                    } else {
                        color = "red";
                    }
                    document.querySelector(`.${houseLabel.classList[3]}`).href = url;
                    style += `
#${houseMarker.id} {
    background-color: ${color} !important;
}
.${houseLabel.classList[3]} .result-price::after {
    content: " $${zestimate}" !important;
}
`
                    addStyle(style);
                });
            } else {
                console.log("error");
            }
        });
}
function xpath(path) {
  return document.evaluate(path, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
}
window.addEventListener ("load", run);