Add titleCase string utility with tests and documentation

README.md

@@ -3,9 +3,10 @@
 A tiny, dependency-free collection of everyday JavaScript utility functions — the kind of small helpers every project ends up writing at some point.
 
 ```js
-const { capitalize, slugify, unique, sum, chunk } = require('pull-toolkit');
+const { capitalize, titleCase, slugify, unique, sum, chunk } = require('pull-toolkit');
 
 capitalize('hello world'); // "Hello world"
+titleCase('hello world');  // "Hello World"
 slugify('Hello, World!');  // "hello-world"
 unique([1, 2, 2, 3]);      // [1, 2, 3]
 sum([1, 2, 3, 4]);         // 10
@@ -39,6 +40,7 @@ npm test
 ### Strings
 
 - `capitalize(str)` — uppercases the first letter of a string.
+- `titleCase(str)` — uppercases the first letter of each whitespace-separated word, preserving spacing and the remaining letters.
 - `slugify(str)` — converts a string into a URL-friendly slug.
 
 ### Arrays

src/strings.js

@@ -4,6 +4,11 @@ function capitalize(str) {
   return str.charAt(0).toUpperCase() + str.slice(1);
 }
 
+/** Capitalizes each whitespace-separated word without changing spacing or other letters. */
+function titleCase(str) {
+  return str.replace(/\S+/g, capitalize);
+}
+
 /** Converts a string into a URL-friendly slug, e.g. "Hello World!" -> "hello-world". */
 function slugify(str) {
   return str
@@ -13,4 +18,4 @@ function slugify(str) {
     .replace(/^-+|-+$/g, '');
 }
 
-module.exports = { capitalize, slugify };
+module.exports = { capitalize, titleCase, slugify };

tests/strings.test.js

@@ -1,6 +1,6 @@
 const { test } = require('node:test');
 const assert = require('node:assert/strict');
-const { capitalize } = require('../src/strings');
+const { capitalize, titleCase } = require('../src/strings');
 
 test('capitalize uppercases the first letter', () => {
   assert.equal(capitalize('hello'), 'Hello');
@@ -9,3 +9,27 @@ test('capitalize uppercases the first letter', () => {
 test('capitalize handles an empty string', () => {
   assert.equal(capitalize(''), '');
 });
+
+test('titleCase uppercases the first letter of every word', () => {
+  assert.equal(titleCase('hello world'), 'Hello World');
+  assert.equal(titleCase('hello'), 'Hello');
+});
+
+test('titleCase handles empty and whitespace-only strings', () => {
+  assert.equal(titleCase(''), '');
+  assert.equal(titleCase(' \t\n'), ' \t\n');
+});
+
+test('titleCase preserves whitespace between and around words', () => {
+  assert.equal(titleCase('  hello\tworld\nfrom  javascript  '), '  Hello\tWorld\nFrom  Javascript  ');
+});
+
+test('titleCase preserves the remaining letters of each word', () => {
+  assert.equal(titleCase('javaScript HTML'), 'JavaScript HTML');
+});
+
+test('titleCase is available from the package entry point', () => {
+  const toolkit = require('../src');
+  assert.equal(toolkit.titleCase, titleCase);
+  assert.equal(toolkit.titleCase('hello world'), 'Hello World');
+});