const regex = /^(M{0,3})(C(?:D|M)|D?C{0,3})(X(?:L|C)|L?X{0,3})(I(?:V|X)|V?I{0,3})$/;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('^(M{0,3})(C(?:D|M)|D?C{0,3})(X(?:L|C)|L?X{0,3})(I(?:V|X)|V?I{0,3})$', '')
const str = ``;
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