Furkan's Notes

Furkan's Notes

@supports rule on CSS

@supports rule on CSS

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Table of Contents

  1. Section
  2. Browser Support
  3. Javascript Usecases
  4. Logic Operators
    1. Not Operator
    2. And Operator
    3. Or Operator
  5. Selector Testing
  6. Links

1. Definition

@supports property allows us to test if the browser supports particular property before applying the styles. It can be same as @media property which applies the styles in particular breakpoint.

The syntax looks like this;

@supports (display: grid) {
  #root {
    display: grid;
  }
}

2. Browser Support

If @supports is supported all the browsers you need then it is time to use it in your applications as well. It gives really nice features that you can control.

Here is the browser support for it;

Browser Support

3. Javascript Usecases

In JavaScript, @supports can be accessed via the CSS object model interface CSSSupportsRule

The CSS includes a CSS feature query using the @supports at-rule, containing one style rule. This will be the first CSSRule returned by document.styleSheets[0].cssRules.myRules[0] therefore returns a CSSSupportsRule object.

let myRules = document.styleSheets[0].cssRules;
console.log(myRules[0]); // a CSSSupportsRule representing the feature query.

Javascript even has an API for this. We can test some properties here as well;

if (window.CSS && window.CSS.supports) {
 // See if API supported in this browser
}
// You can seperate the property and the value.
const supportsGrid = CSS.supports("display", "grid");
// Or you can give all in one
const supportsGrid = CSS.supports("(display: grid)");

4. Logic Operators

4.1. Not operator

It will apply the rules if the specified rule is not true

@supports not (display: grid) {
    #root {
        display: flex;
    }
}

4.2. And operator

It will apply the rules once both of the cases apply true

@supports (display: grid) and (display: flex) {}

4.3. Or operator

It will apply the rules if at least one of them is true

@supports (transform-style: preserve) or (-moz-transform-style: preserve) {}

5. Selector Testing (Experimental)

There is a way to test the support of selectors with @supports in some browsers (Firefox, etc.)

@supports selector(A > B) {
    .container {

    }
}
 
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