const regex = /^[A-Za-z0-9][A-Za-z0-9-.]*\.\D{2,4}$/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('^[A-Za-z0-9][A-Za-z0-9-.]*\\.\\D{2,4}$', 'gm')
const str = `ec2-11-111-222-333.cd-blahblah-1.compute.amazonaws.com
domaine.com
subdomain.domain.com
12533d5.dkkkd.com
2dotsextension.co
1dotextension.c
ekkej_dhh.com
12552.2225
112.25.25
12345.com
12345.123.com
domaine.123
whatever
9999-ee.99
email@domain.com
.jjdj.kkd
-subdomain.domain.com
@subdomain.domain.com
112.25.25
`;
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