Javascript

CSS variables can be accessed and updated in JavaScript, which allows you to accomplish things that were previously very complicated, like dynamically applying style themes. By updating a few key variables based on user input, you can reskin an entire interface.

Update CSS variables in JS by using the setProperty method on the document root’s style property.

document.documentElement.style.setProperty(`--color-primary`, `#4299e1`);

You can also alias variables to other variables, this is useful for using a consistent property throughout your codebase that can be dynamically updated without losing meaning.

function enableDarkMode() {
  document.documentElement.style.setProperty(`--color-background`, `var(--color-black)`);
  document.documentElement.style.setProperty(`--color-text`, `white`)
}