How can I add script to the page

When I use linked a page,I wan to add a very large script file to the page. is there a way effecient working effeciently?

It is highly not recommended. If you really need to do it on page load then you can add it on page init then you can add it using this snippet:

var script = document.createElement('script');
script.src = 'path/to/file.js';