In site optimization and after testing its speed on pingdom
and others it says to combine external JavaScript files. How can I combine them?
Here are the following files which it says to combine, but I have no idea how to combine them.
There are 2 JavaScript files served from mc.yandex.ru. They should be combined into as few files as possible.
https://mc.yandex.ru/metrika/tag.js
https://mc.yandex.ru/watch/47716165/1?wmode=7&p ... 0%26%20Reviews%20in%20UAE%20%7C%20YallaMotor.com
There are 2 JavaScript files served from static.adsafeprotected.com. They should be combined into as few files as possible.
https://static.adsafeprotected.com/sca.17.4.95.js
https://static.adsafeprotected.com/skeleton.js
There are 2 JavaScript files served from www.gstatic.com. They should be combined into as few files as possible.
https://www.gstatic.com/firebasejs/4.10.1/firebase-app.js
https://www.gstatic.com/firebasejs/4.10.1/firebase-messaging.js
How can I combine them into one file?