How to assign javascript array to model array in mvc4?

You can't assign anything in MVC via javascript as MVC code executes on the server and the resultant html and javascript runs on the client. Your server code isn't "running inside" the browser.

To pass things to the model you need to put the data in a form element that then binds to your model property via model binding when the form is submitted. If you google for dealing with mvc arrays and javascript you'll see examples of some techniques that can bind arrays to models. Alternatively you might be better just using ajax to post the array direct to an action; it's hard to tell from your question.