ported from java version http://stackoverflow.com/a/12457269/1798418

colorregex.js

var keywords_color_regex = /^[a-z]*$/;
var hex_color_regex = /^#[0-9a-f]{3}([0-9a-f]{3})?$/;
var rgb_color_regex = /^rgb\(\s*(0|[1-9]\d?|1\d\d?|2[0-4]\d|25[0-5])%?\s*,\s*(0|[1-9]\d?|1\d\d?|2[0-4]\d|25[0-5])%?\s*,\s*(0|[1-9]\d?|1\d\d?|2[0-4]\d|25[0-5])%?\s*\)$/;
var rgba_color_regex = /^rgba\(\s*(0|[1-9]\d?|1\d\d?|2[0-4]\d|25[0-5])%?\s*,\s*(0|[1-9]\d?|1\d\d?|2[0-4]\d|25[0-5])%?\s*,\s*(0|[1-9]\d?|1\d\d?|2[0-4]\d|25[0-5])%?\s*,\s*((0.[1-9])|[01])\s*\)$/;
var hsl_color_regex = /^hsl\(\s*(0|[1-9]\d?|[12]\d\d|3[0-5]\d)\s*,\s*((0|[1-9]\d?|100)%)\s*,\s*((0|[1-9]\d?|100)%)\s*\)$/;

@rokobuljan just fixed that

Note: the rgba regex only allows for a single digit precision for the alpha channel. Adding a + after (0.[1-9]) allows arbitrary precision. Updated value:

- var rgba_color_regex = /^rgba\(\s*(0|[1-9]\d?|1\d\d?|2[0-4]\d|25[0-5])%?\s*,\s*(0|[1-9]\d?|1\d\d?|2[0-4]\d|25[0-5])%?\s*,\s*(0|[1-9]\d?|1\d\d?|2[0-4]\d|25[0-5])%?\s*,\s*((0.[1-9])|[01])\s*\)$/;
+ var rgba_color_regex = /^rgba\(\s*(0|[1-9]\d?|1\d\d?|2[0-4]\d|25[0-5])%?\s*,\s*(0|[1-9]\d?|1\d\d?|2[0-4]\d|25[0-5])%?\s*,\s*(0|[1-9]\d?|1\d\d?|2[0-4]\d|25[0-5])%?\s*,\s*((0.[1-9]+)|[01])\s*\)$/;