What is the regex for xml namespace?

The regex pattern for xml namespace is `xmlns(?::[a-zA-Z][a-zA-Z0-9]*)?\s*=\s*"[^"]*"`. This pattern validates xml namespace declaration (xmlns or xmlns:prefix).

How do I use this regex in JavaScript?

In JavaScript, create the regex with `const regex = /xmlns(?::[a-zA-Z][a-zA-Z0-9]*)?\s*=\s*"[^"]*"/;` and test with `regex.test(yourValue)`. It returns `true` if the value matches.

How do I use this regex in Python?

In Python, use `import re; re.match(r'xmlns(?::[a-zA-Z][a-zA-Z0-9]*)?\s*=\s*"[^"]*"', value)`. The raw string prefix (`r`) prevents Python from interpreting backslashes as escape characters.

Is this regex case-sensitive?

This pattern explicitly handles both uppercase and lowercase via the character classes. No additional flags needed.

Regex for XML Namespace

Regex Pattern

xmlns(?::[a-zA-Z][a-zA-Z0-9]*)?\s*=\s*"[^"]*"

XML namespace declaration (xmlns or xmlns:prefix)

Quick Answer

The regex pattern for xml namespace is `xmlns(?::[a-zA-Z][a-zA-Z0-9]*)?\s*=\s*"[^"]*"`. XML namespace declaration (xmlns or xmlns:prefix). This works in JavaScript, Python, Ruby, PHP, Java, and most regex engines that support PCRE syntax.

Test Examples

Input	Result
xmlns="http://www.w3.org/2000/svg"	✓ Matches
xmlns:xlink="http://www.w3.org/1999/xlink"	✓ Matches
class="value"	✗ No match
xmlns	✗ No match
xmlns=	✗ No match

Code Examples

javascript

const regex = /xmlns(?::[a-zA-Z][a-zA-Z0-9]*)?\s*=\s*"[^"]*"/;
const isValid = regex.test(value);

python

import re
pattern = r'xmlns(?::[a-zA-Z][a-zA-Z0-9]*)?\s*=\s*"[^"]*"'
if re.match(pattern, value):
    print("valid")

ruby

pattern = /xmlns(?::[a-zA-Z][a-zA-Z0-9]*)?\s*=\s*"[^"]*"/
if value =~ pattern
  puts "valid"
end

php

if (preg_match('/xmlns(?::[a-zA-Z][a-zA-Z0-9]*)?\s*=\s*"[^"]*"/', $value)) {
    echo "valid";
}

java

String pattern = "xmlns(?::[a-zA-Z][a-zA-Z0-9]*)?\\s*=\\s*"[^"]*"";
boolean isValid = value.matches(pattern);

Frequently Asked Questions

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