What is the regex for npm package name?

The regex pattern for npm package name is `^(?:@[a-z0-9-~][a-z0-9-._~]*\/)?[a-z0-9-~][a-z0-9-._~]*$`. This pattern validates valid npm package name (scoped or unscoped).

How do I use this regex in JavaScript?

In JavaScript, create the regex with `const regex = /^(?:@[a-z0-9-~][a-z0-9-._~]*\\/)?[a-z0-9-~][a-z0-9-._~]*$/;` 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'^(?:@[a-z0-9-~][a-z0-9-._~]*\/)?[a-z0-9-~][a-z0-9-._~]*$', value)`. The raw string prefix (`r`) prevents Python from interpreting backslashes as escape characters.

Is this regex case-sensitive?

By default, yes. To make it case-insensitive, add the `i` flag in JavaScript (`/^(?:@[a-z0-9-~][a-z0-9-._~]*\/)?[a-z0-9-~][a-z0-9-._~]*$/i`) or use `re.IGNORECASE` in Python.

Regex for npm Package Name

Regex Pattern

^(?:@[a-z0-9-~][a-z0-9-._~]*\/)?[a-z0-9-~][a-z0-9-._~]*$

Valid npm package name (scoped or unscoped)

Quick Answer

The regex pattern for npm package name is `^(?:@[a-z0-9-~][a-z0-9-._~]*\/)?[a-z0-9-~][a-z0-9-._~]*$`. Valid npm package name (scoped or unscoped). This works in JavaScript, Python, Ruby, PHP, Java, and most regex engines that support PCRE syntax.

Test Examples

Input	Result
react	✓ Matches
@types/node	✓ Matches
my-package	✓ Matches
@scope/my-lib	✓ Matches
React	✗ No match
MY_PACKAGE	✗ No match
.hidden	✗ No match
_private	✗ No match

Code Examples

javascript

const regex = /^(?:@[a-z0-9-~][a-z0-9-._~]*\\/)?[a-z0-9-~][a-z0-9-._~]*$/;
const isValid = regex.test(value);

python

import re
pattern = r'^(?:@[a-z0-9-~][a-z0-9-._~]*\/)?[a-z0-9-~][a-z0-9-._~]*$'
if re.match(pattern, value):
    print("valid")

ruby

pattern = /^(?:@[a-z0-9-~][a-z0-9-._~]*\/)?[a-z0-9-~][a-z0-9-._~]*$/
if value =~ pattern
  puts "valid"
end

php

if (preg_match('/^(?:@[a-z0-9-~][a-z0-9-._~]*\\/)?[a-z0-9-~][a-z0-9-._~]*$/', $value)) {
    echo "valid";
}

java

String pattern = "^(?:@[a-z0-9-~][a-z0-9-._~]*\\/)?[a-z0-9-~][a-z0-9-._~]*$";
boolean isValid = value.matches(pattern);

Frequently Asked Questions

Related Regex Patterns

JavaScript Variable Name

Valid JavaScript variable/identifier name

Python Variable Name

Valid Python identifier name

CSS Class Name

Valid CSS class name (starts with letter, underscore, or hyphen)

CSS ID Selector

CSS ID selector starting with #

JSON Key

JSON object key (quoted string followed by colon)

Semantic Version (Strict)

Strict semantic versioning (MAJOR.MINOR.PATCH)