set css var with js code example

Example 1: javascript get css variable

let docStyle = getComputedStyle(document.documentElement);

//get variable
let myVarVal docStyle.getPropertyValue('--my-variable-name');

//set variable
docStyle.setProperty('--my-variable-name', '#fff');

Example 2: set css variable from javascript

document.documentElement.style.cssText = "--tab-count: 3";
/or/
document.documentElement.style.setProperty("--tab-count", 5);
/or/
document.documentElement.setAttribute("style", "--tab-count: 5");

Example 3: how to change css variable in javascript

document.documentElement.setAttribute("style", "--main-background-color: green");

Example 4: js set css variable

document.documentElement.style.setProperty("--main-background-color", "green");