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Capitalize a String

capitalizeString​

The capitalizeString function converts the first letter of a given string to uppercase while keeping the rest lowercase (unless otherwise specified). It provides flexible options to capitalize all letters, each word’s first letter, or retain the original casing.

Function Signature​

function capitalizeString(string: string, options?: CapitalizeOptions): string;

Parameters​

  • string: The string to capitalize.
  • options (optional): Customization options for capitalization:
    • capitalizeEachFirst (boolean): Capitalizes the first letter of each word. Defaults to false.
    • capitalizeAll (boolean): Converts the entire string to uppercase. Defaults to false.
    • lowerCaseRest (boolean): Ensures all characters except the first are lowercase. Defaults to true.

Return Value​

Returns a string with capitalization applied based on the provided options:

  • Default behavior: Only the first letter is capitalized, and the rest is lowercase.
  • If capitalizeEachFirst: true, the first letter of every word is capitalized.
  • If capitalizeAll: true, the entire string is converted to uppercase.
  • If lowerCaseRest: false, the remaining letters retain their original casing.

Example Usage​

Import​

import { capitalizeString } from 'nhb-toolbox';

Basic Capitalization​

capitalizeString('hello world'); 
// Output: 'Hello world'

Capitalizing Each Word​

capitalizeString('hello world', { capitalizeEachFirst: true });
// Output: 'Hello World'

Converting Entire String to Uppercase​

capitalizeString('hello world', { capitalizeAll: true });
// Output: 'HELLO WORLD'

Keeping the Rest of the String's Case Intact​

capitalizeString('hello WORLD', { lowerCaseRest: false });
// Output: 'Hello WORLD'

Edge Cases Handled​

  • If the input is an empty string or not a valid string, it returns an empty string.
  • It correctly handles strings with leading/trailing whitespace.
  • Supports punctuation and special characters while preserving them.

Types​

CapitalizeOptions​

interface CapitalizeOptions {
  capitalizeEachFirst?: boolean;
  capitalizeAll?: boolean;
  lowerCaseRest?: boolean;
}

Conclusion​

The capitalizeString function provides a versatile way to format text with precise capitalization rules, handling various cases such as entire-string uppercase, word-based capitalization, and preservation of casing when needed.