const regex = /(?<=#00FF|#FF00)[A-Fa-f0-9]{2}|[A-Fa-f0-9]{2}(?=00FF|FF00)|(?<=#00)[A-Fa-f0-9]{2}(?=FF)|(?<=#FF)[A-Fa-f0-9]{2}(?=00)/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('(?<=#00FF|#FF00)[A-Fa-f0-9]{2}|[A-Fa-f0-9]{2}(?=00FF|FF00)|(?<=#00)[A-Fa-f0-9]{2}(?=FF)|(?<=#FF)[A-Fa-f0-9]{2}(?=00)', 'gm')
const str = `Correct cases:
#FF0012
#00FFAB
#0034FF
#CD00FF
#56FF00
#FF7800
Incorrect cases:
#0000AA
#FFFFBB
#00CC00
#FFDDFF
#EE0000
#FFFFFF`;
// Reset `lastIndex` if this regex is defined globally
// regex.lastIndex = 0;
let m;
while ((m = regex.exec(str)) !== null) {
// This is necessary to avoid infinite loops with zero-width matches
if (m.index === regex.lastIndex) {
regex.lastIndex++;
}
// The result can be accessed through the `m`-variable.
m.forEach((match, groupIndex) => {
console.log(`Found match, group ${groupIndex}: ${match}`);
});
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions