Workaround for CSS variables in IE?

Question

I'm currently developing a web application in Outsystems in which I have the need to customize the CSS, in which I'm using variables. I need to guarantee the app works cross-browser, including in Internet Explorer. IE doesn't support CSS variables, as you can see in the picture below from this source.

Since I have to use CSS variables, is there any workaround for the usage of variables in IE?

Answer 1

Yes there is a way, the same way you make any css compatible: use a specific css fallback that is supported by the browser.

body {   --text-color: red; }  body {   color: red; /* default supported fallback style */   color: var(--text-color); /* will not be used by any browser that doesn't support it, and will default to the previous fallback */ } 

This solution is incredibly redundant and 'almost' defeats the purpose of css variables....BUT it is necessary for browser compatibility. Doing this would essentially make the css variables useless but I implore you to still use them because it will serve as an important reminder to the fact that these values are referenced elsewhere and need to be updated in all cases, otherwise you forget to update every related occurrence of 'color' and then you have inconsistent styling because relevant css values are out of sync. The variable will serve more as a comment but a very important one.

Answer 2

There is a polyfill, which enables almost complete support for CSS variables in IE11:
https://github.com/nuxodin/ie11CustomProperties
(i am the author)

The script makes use of the fact that IE has minimal custom properties support where properties can be defined and read out with the cascade in mind.
.myEl {-ie-test:'aaa'} // only one dash allowed! "-"
then read it in javascript:
getComputedStyle( querySelector('.myEl') )['-ie-test']

From the README:

Features

• handles dynamic added html-content
• handles dynamic added , -elements
• chaining --bar:var(--foo)
• fallback var(--color, blue)
• :focus, :target, :hover
• js-integration:
  • style.setProperty('--x','y')
  • style.getPropertyValue('--x')
  • getComputedStyle(el).getPropertyValue('--inherited')
• Inline styles: <div ie-style="--color:blue"...
• cascade works
• inheritance works
• under 3k (min+gzip) and dependency-free

Demo:

https://rawcdn.githack.com/nuxodin/ie11CustomProperties/b851ec2b6b8e336a78857b570d9c12a8526c9a91/test.html