const regex = /\A(?=\D*\d)(?=[^A-Z]*[A-Z][^A-Z]*\z)[A-Za-z\d]{4}\z/;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('\\A(?=\\D*\\d)(?=[^A-Z]*[A-Z][^A-Z]*\\z)[A-Za-z\\d]{4}\\z', '')
const str = `e3Wd`;
// Reset `lastIndex` if this regex is defined globally
// regex.lastIndex = 0;
let m;
if ((m = regex.exec(str)) !== null) {
// 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