How to integrate JS version of yoast ?

You can find JS version of Yoast on github there is a javascript version of it that can be added to custom sites here is the steps that you need to follow

npm install -g browserify

in order to convert this or any kind of nodejs library to browser javascript supported just go to browserify . first install it by

then install all the library it needs with

npm install module_name

at the end generate single js file with

browserify main.js -o file.js

now you can add script to your html like

<script src="file.js"></script>

for YOAST library there is a browserify directory in example. I use browserify for the index.js file at root directory and add the generated file to this example html file and everything works like a charm.