Variables & JavaScript
Change Variables With JavaScript
Because CSS variables are accessible through the DOM, JavaScript can be used to modify them.
This is an illustration of how to write a script that will show and modify the –blue variable from the earlier pages. For the time being, it’s okay if you don’t know anything about JavaScript. See our JavaScript Tutorial for additional information about JavaScript:
Example
<script>
// Get the root element
var r = document.querySelector(':root');
// Create a function for getting a variable value
function myFunction_get() {
// Get the styles (properties and values) for the root
var rs = getComputedStyle(r);
// Alert the value of the --blue variable
alert("The value of --blue is: " + rs.getPropertyValue('--blue'));
}
// Create a function for setting a variable value
function myFunction_set() {
// Set the value of variable --blue to another value (in this case "lightblue")
r.style.setProperty('--blue', 'lightblue');
}
</script>
Browser Support
The numbers in the table specify the first browser version that fully supports the var() function.
CSS var() Function
| Property | Description |
|---|---|
| var() | Inserts the value of a CSS variable |
