capitalize

Capitalizes the first letter of a string and lowercases the rest.

capitalize

Signature

function capitalize(str: string): string

Parameters

• str - The string to capitalize

Returns

String with first character uppercase and remaining characters lowercase.

Examples

import { capitalize } from 'strio'

// Basic usage
capitalize('hello world')
// "Hello world"

capitalize('HELLO WORLD')
// "Hello world"

capitalize('hELLo WoRLd')
// "Hello world"

// Empty strings
capitalize('')
// ""

// Single character
capitalize('h')
// "H"

// With special characters
capitalize('!hello')
// "!hello"

// Non-Latin characters
capitalize('привет мир')
// "Привет мир"

// Null/undefined safety
capitalize(null)      // ""
capitalize(undefined) // ""

Use Cases

Format User Input

import { capitalize, trim } from 'strio'

function formatName(name: string): string {
  return capitalize(trim(name))
}

formatName('  JOHN DOE  ')
// "John doe"

Sentence Formatting

import { capitalize } from 'strio'

function formatSentence(text: string): string {
  return capitalize(text.toLowerCase())
}

formatSentence('HELLO EVERYONE!')
// "Hello everyone!"

Form Field Normalization

import { capitalize } from 'strio'

const cityInput = document.getElementById('city')
cityInput.addEventListener('blur', (e) => {
  e.target.value = capitalize(e.target.value)
})
// User types "NEW YORK" → converts to "New york"

Related Functions

• capitalizeWords - Capitalize each word
• titleCase - Grammar-aware title case
• humanize - Make readable from code

See Also

• String Manipulation Guide
• Humanize Functions