Single or Double Colon for CSS Pseudo-elements: Which Notation Should You Use?

The Double-Colon Dilemma: Single or Double for Pseudo-Elements?

In the world of CSS pseudo-elements, the single- (e.g., :after) and double-colon (e.g., ::after) notations have sparked a debate among developers. Given that IE7 and IE8 lack support for double-colon, some question whether it's prudent to use the single-colon solely, with the option of reverting back later.

The Argument for Single Colon Now

Advocates of using only the single-colon notation cite the widespread support for it in modern browsers. This approach eliminates the need for separate rules for backwards compatibility with IE7 and IE8.

The Case for Double Colon

Others argue that using double-colon alongside single-colon, as seen in the code sample:

.foo:after,
.foo::after { /*styles*/ }

provides additional flexibility. By including double-colon rules, developers can target future browsers that may offer enhanced styling options specific to double-colon pseudo-elements.

Warning: Avoid Combined Notation

It's crucial to note that using both single and double colons in a single rule, separated by a comma, is strongly discouraged. Browsers may ignore the entire rule if it includes syntax errors, such as the combination of single and double colons.

Recommendation: Single Colon for Now

For maximum compatibility and simplicity, it's recommended to stick with the single-colon notation for the time being. As IE7 and IE8 fade into obscurity, developers can then reassess the use of double-colon notation for potential enhancements.

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