@rbxts/jsnatives

toSentenceCase

Converts a string to Sentence case format.

Signature

function toSentenceCase(str: string): string

Description

The toSentenceCase function converts a string to Sentence case format, where only the first letter of the entire string is capitalized and the rest of the letters are lowercase. This is typically used for sentences or phrases.

Parameters

str: The string to convert to Sentence case.

Return value

A new string in Sentence case format.

Examples

Basic usage

// Converting different formats to Sentence case
const space = String.toSentenceCase("hello world");
print(space); // Outputs: "Hello world"

const camel = String.toSentenceCase("helloWorld");
print(camel); // Outputs: "Hello world"

const pascal = String.toSentenceCase("HelloWorld");
print(pascal); // Outputs: "Hello world"

const snake = String.toSentenceCase("hello_world");
print(snake); // Outputs: "Hello world"

const kebab = String.toSentenceCase("hello-world");
print(kebab); // Outputs: "Hello world"

Multiple words

// Converting multi-word strings
const multiple = String.toSentenceCase("hello beautiful world");
print(multiple); // Outputs: "Hello beautiful world"

const mixedSeparators = String.toSentenceCase("hello_beautiful-world");
print(mixedSeparators); // Outputs: "Hello beautiful world"

Handling edge cases

// Empty string
const empty = String.toSentenceCase("");
print(empty); // Outputs: ""

// Single word
const single = String.toSentenceCase("hello");
print(single); // Outputs: "Hello"

// All uppercase
const uppercase = String.toSentenceCase("HELLO WORLD");
print(uppercase); // Outputs: "H e l l o w o r l d" (each uppercase is treated as new word)

// Already in Sentence case
const alreadySentence = String.toSentenceCase("Hello world");
print(alreadySentence); // Outputs: "Hello world"

Converting from other cases

// From Title case
const title = String.toSentenceCase("This Is A Title");
print(title); // Outputs: "This is a title"

// From camelCase
const camel = String.toSentenceCase("userFirstName");
print(camel); // Outputs: "User first name"

// From PascalCase
const pascal = String.toSentenceCase("UserLoginRequest");
print(pascal); // Outputs: "User login request"

// From snake_case
const snake = String.toSentenceCase("user_first_name");
print(snake); // Outputs: "User first name"

// From kebab-case
const kebab = String.toSentenceCase("api-response-code");
print(kebab); // Outputs: "Api response code"

Practical applications

// Format text for display
function formatDescription(description: string): string {
  return String.toSentenceCase(description);
}

print(formatDescription("the_quick_brown_fox_jumps_over_the_lazy_dog"));
// Outputs: "The quick brown fox jumps over the lazy dog"

// Format error messages
function formatErrorMessage(error: string): string {
  // Ensure first letter is capitalized and rest is lowercase
  return String.toSentenceCase(error);
}

print(formatErrorMessage("FILE_NOT_FOUND")); // Outputs: "File not found"
print(formatErrorMessage("invalidUserInput")); // Outputs: "Invalid user input"

Multiple sentences

// Note: toSentenceCase only capitalizes the first letter of the entire string,
// not each sentence within a paragraph

const paragraph = String.toSentenceCase("hello world. this is a test. another sentence.");
print(paragraph); // Outputs: "Hello world. this is a test. another sentence."

// To capitalize each sentence, you would need a custom function:
function capitalizeEachSentence(text: string): string {
  // Split by sentence ending punctuation followed by a space
  const sentences = String.split(text, "%. ");

  // Capitalize each sentence
  const capitalizedSentences = sentences.map(sentence =>
    String.toSentenceCase(sentence)
  );

  // Join back with periods
  return capitalizedSentences.join(". ");
}

const proper = capitalizeEachSentence("hello world. this is a test. another sentence.");
print(proper); // Outputs: "Hello world. This is a test. Another sentence."