how to link css file in html using javascript code example

Example 1: how to link javascript to html and css

# Javascript
<script src="[file_name].js"></script>

# CSS
<link rel = "stylesheet" type="text/css" href = "style.css" />

Example 2: javascript add css file

var cssFile = document.createElement('link');
    cssFile.rel = 'stylesheet';
    cssFile.href = "styles.css";  // or path for file {themes('/styles/mobile.css')}
    document.head.appendChild(cssFile); // append css to head element