Javascript Interview Question: Title Case - Capitalize the first letter in each word of a string.

capitalize.js

/*
 Create a function that accepts a string, converts the string to title case, and
 returns the result. For title case, the first letter of each word is capitalized.
 
 capitalize('hello world'); //Outputs: 'Hello World'
 captialize('the year of the hare'); //Outputs: 'The Year Of The Hare';
 
 Pseudo code:
  1. Split the string into array using str.split(' ');
  2. Map over the elements in the array. Title case each word using helper function.
  3. Join the elements of the newly defined array separated by space.
  4. Return the result.
 */

function capitalize(str) {
  return str.split(' ').map(word => titleCase(word)).join(' ');
}

//Helper function to capitalize a single word.
function titleCase(word) {
  return word[0].toUpperCase() + word.slice(1);
}

//Try it
console.log(capitalize('arto paasilinna'));