What is an example of a matching and non-matching string?

A valid matching string is "0x71C8451C3343244F0080644085429188e7D4d715". A non-matching string is "71C8451C3343244F0080644085429188e7D4d715".

Is this regex safe from ReDoS (Catastrophic Backtracking)?

Yes, this pattern is optimized for linear execution time and safe for browser-side validation without locking up the UI thread.

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Ethereum (ETH) Address Regex

Q: How do I test this regex in JavaScript and TypeScript?

Use regex.test(): const regex = /^0x[a-fA-F0-9]{40}$/; const isValid = regex.test(inputString);

Validates Ethereum and EVM-compatible (Polygon, Arbitrum, BSC) public account and contract hexadecimal addresses.

Regular Expression Pattern:

/^0x[a-fA-F0-9]{40}$/

Valid Match Example:

0x71C8451C3343244F0080644085429188e7D4d715

Invalid / Non-Match Example:

71C8451C3343244F0080644085429188e7D4d715

Regex Syntax Breakdown & Explanation

•^0x : Mandatory hexadecimal prefix
•[a-fA-F0-9]{40}$ : Exactly 40 hexadecimal characters representing 20-byte address hash

Implementation in Popular Languages

JavaScript / TypeScript

const regex = /^0x[a-fA-F0-9]{40}$/;
const isValid = regex.test("0x71C8451C3343244F0080644085429188e7D4d715");
console.log(isValid); // true

Python (re)

import re

pattern = r"^0x[a-fA-F0-9]{40}$"
match = re.match(pattern, "0x71C8451C3343244F0080644085429188e7D4d715")
print(bool(match)) # True

Go (regexp)

package main
import (
  "fmt"
  "regexp"
)

func main() {
  re := regexp.MustCompile(`^0x[a-fA-F0-9]{40}$`)
  fmt.Println(re.MatchString("0x71C8451C3343244F0080644085429188e7D4d715"))
}

Frequently Asked Questions

Everything you need to know regarding specifications, syntax, and security best practices.

The regular expression pattern is /^0x[a-fA-F0-9]{40}$/. Validates Ethereum and EVM-compatible (Polygon, Arbitrum, BSC) public account and contract hexadecimal addresses.