how to add css to document using js code example

Example 1: how to give css style in javascript

document.getElementById("myH1").style.color = "red";

Example 2: js add css style to element

// Create our stylesheet
var style = document.createElement('style');
style.innerHTML =
	'.some-element {' +
		'color: purple;' +
		'background-color: #e5e5e5;' +
		'height: 150px;' +
	'}';

// Get the first script tag
var ref = document.querySelector('script');

// Insert our new styles before the first script tag
ref.parentNode.insertBefore(style, ref);

Example 3: js add css to document

document.querySelector('head').innerHTML += '<link rel="stylesheet" href="styles.css" type="text/css"/>';