Case Converter

About Case Converter

This tool performs text case transformations for writing, editing, and code formatting workflows. It handles standard case formats (UPPERCASE, lowercase, Title Case, Sentence case) plus programming conventions and special formats.

Text Case Format Reference

Title Case Rules by Style Guide

Different style guides have varying Title Case rules:

Case Conversion Algorithm

JavaScript Case Transformation Functions:

// UPPERCASE - simple toUpperCase()
function toUpperCase(text) {
  return text.toUpperCase();
}

// lowercase - simple toLowerCase()
function toLowerCase(text) {
  return text.toLowerCase();
}

// Title Case - capitalize major words
function toTitleCase(text) {
  const minorWords = ['a', 'an', 'the', 'and', 'but', 'or', 'nor',
                      'for', 'so', 'yet', 'in', 'on', 'at', 'to',
                      'by', 'of', 'with', 'as'];
  return text.toLowerCase().split(' ').map((word, i) => {
    if (i === 0 || i === words.length - 1) {
      return word.charAt(0).toUpperCase() + word.slice(1);
    }
    if (minorWords.includes(word)) return word;
    return word.charAt(0).toUpperCase() + word.slice(1);
  }).join(' ');
}

// Sentence case - capitalize first letter of sentences
function toSentenceCase(text) {
  return text.toLowerCase().replace(/(^\s*\w|[\.\!\?]\s*\w)/g, c =>
    c.toUpperCase()
  );
}

Programming Language Naming Conventions

Case Conversion Examples

Input: "the quick brown fox jumps over the lazy dog"
─────────────────────────────────────────────────────
UPPERCASE:      THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
lowercase:      the quick brown fox jumps over the lazy dog
Title Case:     The Quick Brown Fox Jumps Over the Lazy Dog
Sentence case:  The quick brown fox jumps over the lazy dog
camelCase:      theQuickBrownFoxJumpsOverTheLazyDog
PascalCase:     TheQuickBrownFoxJumpsOverTheLazyDog
snake_case:     the_quick_brown_fox_jumps_over_the_lazy_dog
kebab-case:     the-quick-brown-fox-jumps-over-the-lazy-dog
SCREAMING:      THE_QUICK_BROWN_FOX_JUMPS_OVER_THE_LAZY_DOG

Readability Research

• UPPERCASE readability: Studies show all-caps text is 13-20% slower to read due to lack of letter shape variation (word superiority effect)
• Sentence case optimal: Default case for body text—familiar pattern reduces cognitive load
• Title Case for short text: Effective for headings under 10 words; longer titles become harder to scan
• mixedCase recognition: camelCase and PascalCase improve identifier recognition in code vs underscore variants (Binkley et al., 2006)

Edge Cases and Special Handling

• Acronyms: "NASA" → lowercase "nasa" loses meaning; consider preserving known acronyms
• Proper nouns: "john smith" → Title Case "John Smith" requires name detection
• Hyphenated words: "state-of-the-art" → Title Case varies by style guide
• Unicode characters: Non-ASCII letters (é, ñ, ü) may not transform correctly in all environments
• Turkish I problem: Turkish has dotted İ and dotless ı—toUpperCase/toLowerCase behave differently