Question 380527 in Javascript Question posted in
A very good W3school tutorial can be found here.

Javascript – Failing to pass CamelCase test

I’m struggling with this exercise:

Given is a string n. The task is to return the sentence in CamelCase notation. This means that each new word is capitalized and immediately appended to the old word. Start with a lowercase letter.

I’ve tried this:

function camelCase(s) {
  let result = "";

  // Convert the first character to lowercase
  result += s[0].toLowerCase();

  for (let i = 1; i < s.length; i++) {
    // Check for spaces and capitalize the next character
    if (s[i] === ' ') {
      result += s[i + 1].toUpperCase();
      i++; // Skip the space character
    } else {
      result += s[i];
    }
  }

  return result;
}

but get this error: https://phpout.com/wp-content/uploads/2024/04/duZVr.png

Tags:

2

Answers


  1. 0

    You can see from the comments that any string that ends with an empty character will cause the crash.

    Example: "Hi " will crash your code because there is no character after " " to convert to an upper case. The easiest way to handle this is with a simple condition before the crashing line ie:

    ...
if (s[i] === ' '){
  if (!s[i + 1]) break; // Break since we are at the end of the sentence
  result += s[i + 1].toUpperCase();
...

    This checks to see if there is a character at the end and if not, it just breaks.

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  2. 0

    You should check whether the next character exists, as mentioned in another answer: if (!s[i + 1]) break;.
    But you could probably simplify the code checking the previous character instead.

    Also your comment i++; // Skip the space character – we skip the next character already added to the result instead.

    Also you might want to trim the input string, since leading spaces will result in a wrong output:

    function camelCase(s) {
  let result = "";
  s = s.trim();
  result += s[0].toLowerCase();
  for (let i = 1; i < s.length; i++) {
    if(s[i] !== ' ') result += s[i-1] === ' ' ? s[i].toUpperCase() : s[i];
  }

  return result;
}

console.log(JSON.stringify(camelCase(' Hello world ! ')))

    Trimming the leading spaces in the loop:

    function camelCase(s) {
  let result = "";
  for (let i = 0; i < s.length; i++) {
    if(s[i] !== ' ') 
      if(result.length) 
        result += s[i-1] === ' ' ? s[i].toUpperCase() : s[i];
      else result += s[i].toLowerCase();
  }

  return result;
}

console.log(JSON.stringify(camelCase(' Hello world ! ')))

    Array#reduce() variant:

    const camelCase = s => [...s.trim()].reduce((r, c, i, arr) => 
  (i ? c === ' ' || (r += arr[i - 1] === ' ' ? c.toUpperCase() : c) : r += c.toLowerCase(), r), '');

console.log(JSON.stringify(camelCase(' Hello world ! ')))
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