What is the regex for camelcase word?

The regex pattern for camelcase word is `^[a-z][a-zA-Z0-9]*$`. This pattern validates camelcase identifier (starts lowercase, no separators).

How do I use this regex in JavaScript?

In JavaScript, create the regex with `const regex = /^[a-z][a-zA-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-z][a-zA-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-z][a-zA-Z0-9]*$/i`) or use `re.IGNORECASE` in Python.

Regex for camelCase Word

Regex Pattern

^[a-z][a-zA-Z0-9]*$

camelCase identifier (starts lowercase, no separators)

Quick Answer

The regex pattern for camelcase word is `^[a-z][a-zA-Z0-9]*$`. camelCase identifier (starts lowercase, no separators). This works in JavaScript, Python, Ruby, PHP, Java, and most regex engines that support PCRE syntax.

Test Examples

Input	Result
myVariable	✓ Matches
firstName	✓ Matches
getData	✓ Matches
parseJSON	✓ Matches
MyVariable	✗ No match
my_variable	✗ No match
my-var	✗ No match
UPPER	✗ No match

Code Examples

javascript

const regex = /^[a-z][a-zA-Z0-9]*$/;
const isValid = regex.test(value);

python

import re
pattern = r'^[a-z][a-zA-Z0-9]*$'
if re.match(pattern, value):
    print("valid")

ruby

pattern = /^[a-z][a-zA-Z0-9]*$/
if value =~ pattern
  puts "valid"
end

php

if (preg_match('/^[a-z][a-zA-Z0-9]*$/', $value)) {
    echo "valid";
}

java

String pattern = "^[a-z][a-zA-Z0-9]*$";
boolean isValid = value.matches(pattern);

Frequently Asked Questions

Related Regex Patterns

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Markdown Bold

Markdown bold text (**text** or __text__)

Markdown Code Block

Markdown fenced code block opening/closing delimiter

snake_case Word

snake_case identifier (lowercase with underscores)