javascript using tampermonkey or greasemonkey

change-arabic-font.js

// ==UserScript==
// @name        Arabic font size fixer
// @namespace   Arminius99
// @include     *.wikipedia.org*
// @include     *.wiktionary.org*
// @include     *.aljazeera.net*
// @include     *reddit.com*
// @include     *web.whatsapp.com*
// @include     *.wordpress.com*
// @include     *.facebook.com*
// @description Increases the font size of Arabic text
// @grant       GM_addStyle
// ==/UserScript==

// adjust font, font size and font color according to your preferences
//GM_addStyle("span[lang~='ar'] {font-family: 'Droid Arabic Naskh'; direction: rtl; font-size: 100% !important; }");
//GM_addStyle("span[lang~='ar'] {font-family: 'Sakkal Majalla'; direction: rtl; font-size: 130% !important; }");
GM_addStyle("span[lang~='ar'] {font-family: 'Traditional Arabic'; direction: rtl; font-size: x-large !important; }");

// code by James Padolsey; http://james.padolsey.com/javascript/find-and-replace-text-with-javascript/
function findAndReplace(searchText, replacement, searchNode) {
    if (!searchText || typeof replacement === 'undefined') {
        // Throw error here if you want...
        return;
    }
    var regex = typeof searchText === 'string' ?
                new RegExp(searchText, 'g') : searchText,
        childNodes = (searchNode || document.body).childNodes,
        cnLength = childNodes.length,
        excludes = 'html';
    while (cnLength--) {
        var currentNode = childNodes[cnLength];
        if (currentNode.nodeType === 1 &&
            (excludes + ',').indexOf(currentNode.nodeName.toLowerCase() + ',') === -1) {
            arguments.callee(searchText, replacement, currentNode);
        }
        if (currentNode.nodeType !== 3 || !regex.test(currentNode.data) ) {
            continue;
        }
        var parent = currentNode.parentNode,
            frag = (function(){
                var html = currentNode.data.replace(regex, replacement),
                    wrap = document.createElement('div'),
                    frag = document.createDocumentFragment();
                wrap.innerHTML = html;
                while (wrap.firstChild) {
                    frag.appendChild(wrap.firstChild);
                }
                return frag;
            })();
        parent.insertBefore(frag, currentNode);
        parent.removeChild(currentNode);
    }
}

findAndReplace('([\u0600-\u06FF]+( [\u0600-\u06FF]+)*)', '<span lang="ar">$1</span>');