IPv4 Address in JS
Match valid IPv4 addresses with each octet constrained to 0–255.
Try it in the JS tester →Pattern
regexJS
(?:(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.){3}(?:25[0-5]|2[0-4]\d|[01]?\d\d?) (flags: g)JavaScript / ECMAScript code
jsJavaScript
const re = new RegExp("(?:(?:25[0-5]|2[0-4]\\d|[01]?\\d\\d?)\\.){3}(?:25[0-5]|2[0-4]\\d|[01]?\\d\\d?)", "g");
const input = "192.168.1.1";
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
Each octet alternation covers 250-255, 200-249, and 0-199 ranges to ensure strict 0-255 validity. Three octets with dots are matched, then the final octet.
Examples
Input
192.168.1.1Matches
192.168.1.1
Input
255.255.255.0Matches
255.255.255.0
Input
999.999.999.999No match
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