fetchTest.js

var url = `${location.protocol}/${wbinfo.proxy_magic}/proxy-fetch/https://www.google.com`
var res = await fetch(url)
console.log(await res.text())

styleSRCSETRandom.js

var srcsetSplit = /\s*(\S*\s+[\d.]+[wx]),|(?:\s*,(?:\s+|(?=https?:)))/;
elemCache = window.elemCache ||  new WeakSet();

function getSrcsets() {
    var ssElems = document.querySelectorAll('*[srcset]');
    var ssElem;
    var i = 0;
    var j, length2;
    var length = ssElems.length;
    var values = [];
    var ssValues;
    for (; i < length; ++i) {
        ssElem = ssElems[i];
        if (elemCache.has(ssElem)) {
            continue;
        }
        elemCache.add(ssElem);
        ssValues = ssElem.srcset.split(srcsetSplit);
        j = 0;
        length2 = ssValues.length;
        while (j < length2) {
            if (Boolean(ssValues[j])) {
                values.push(ssValues[j].split(' ')[0]);
            }
            j += 1;
        }
    }
    return values;
}

// getSrcsets()

function corsFetch (it) {
  return fetch(`https://cors-anywhere.herokuapp.com/${it}`, {
    method: 'GET',
    headers: new Headers({'Origin': location.origin})
  }).then(res => res.text())
}

function getStyleSheets () {
    var styleSheets = document.styleSheets;
    var i = 0;
    var styleTag = document.createElement('style');
    document.body.append(styleTag);
    var length = styleSheets.length;
    var ruleValues = [];
    for(; i < length; ++i) {
        try {
            ruleValues.push(Promise.resolve(styleSheets[i].cssRules))
        } catch(error) {
            ruleValues.push(corsFetch(styleSheets[i].href).then(text => {
                styleTag.innerText = text;
                return styleTag.sheet.cssRules;
            }).catch(error => null)); 
        }
    }
    return Promise.all(ruleValues);
}

getStyleSheets().then(vals => console.log(vals)).catch(error => console.error(error));