isLowerCase

Checks if a string is in lowercase.

isLowerCase

Signature

function isLowerCase(str: string): boolean

Parameters

• str - The string to check

Returns

true if all letters are lowercase, false otherwise.

Examples

import { isLowerCase } from 'strio'

// Lowercase
isLowerCase('hello')
// true

isLowerCase('hello123')
// true

isLowerCase('a')
// true

// Not lowercase
isLowerCase('Hello')
// false

isLowerCase('HELLO')
// false

isLowerCase('HeLLo')
// false

// No letters
isLowerCase('123')
// false

isLowerCase('!@#')
// false

isLowerCase('')
// false

Use Cases

import { isLowerCase } from 'strio'

// Enforce lowercase
function ensureLowerCase(input: string): string {
  if (!isLowerCase(input)) {
    console.warn('Input should be lowercase')
    return input.toLowerCase()
  }
  return input
}

// Validate slug
function isValidSlug(slug: string): boolean {
  const cleaned = slug.replace(/[-_]/g, '')
  return cleaned.length > 0 && isLowerCase(cleaned) && isAlphaNumeric(cleaned.replace(/[-_]/g, ''))
}

isValidSlug('my-blog-post')
// true

isValidSlug('My-Blog-Post')
// false

Related Functions

• isUpperCase - Check if uppercase
• capitalize - Capitalize first letter
• slugify - Create URL slug

See Also

• String Validation Guide
• API Reference