Positive Lookahead (Password) in JS
Use positive lookahead `(?=...)` to require the password contain at least one digit and one uppercase letter.
Try it in the JS tester →Pattern
regexJS
^(?=.*\d)(?=.*[A-Z])[A-Za-z\d]{8,}$JavaScript / ECMAScript code
jsJavaScript
const re = new RegExp("^(?=.*\\d)(?=.*[A-Z])[A-Za-z\\d]{8,}$", "");
const input = "Password1";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));Uses `String.prototype.matchAll` for global iteration (Node 12+ / all modern browsers).
How the pattern works
(?=.*\d) is a zero-width assertion that requires the rest of the string to contain a digit somewhere. (?=.*[A-Z]) similarly requires an uppercase letter. Neither consumes characters. [A-Za-z\d]{8,}$ then matches the actual password content (≥8 alphanumerics). Lookaheads are supported in JS and Python; Go's RE2 does NOT support them.
Examples
Input
Password1Matches
Password1
Input
weakpassNo match
—Input
ALLCAPSNODIGITNo match
—