Intermediate Algorithm Scripting - Spinal Tap Case

Challenge: Intermediate Algorithm Scripting - Spinal Tap Case

I hate reGex with all my heart, but here is what I came up with. Do you detect any flaws in here? Can it be optimized? Any recommendations for me based on this code? It passes the test but I spent like 3 hours to do this.

Your code so far

function spinalCase(str) {

let p = str
.replace(/\s|_/g,' ')
.replace(/-/g,' ')
.join(' ')

var x = p.trim().replace(/\s+/g,'-').toLowerCase()

return x


console.log(spinalCase("AllThe-small Things"))

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Challenge: Intermediate Algorithm Scripting - Spinal Tap Case

Link to the challenge:

Hey, it passes the tests, so there are no flaws as far as that goes. You could combine the first two replaces. You don’t need p and x, you could write this as one return statement. And if you wanted to brush up on lookaheads you could simplify this quite a bit (you wouldn’t need any replaces). But you are still learning, so don’t knock yourself too much over not having the “perfect” solution.

Now that you have solved it you could look at the solutions in the hints. Solution 3 uses a lookahead and is the most concise. I would study that one for sure to make sure you understand how it works.

1 Like

If you hate regex, here is an interesting way to tackle this that might give you some ideas to research:

class CapitalOrNonletterSplit {
  [Symbol.split](string) {
    const lower = string.toLowerCase();
    const splitString = [];
    let head = 0;
    for (let i = 0; i < string.length; i++) {
      // Split on and remove non-letter characters
      if (lower[i].charCodeAt(0) < 'a'.charCodeAt(0) ||
          lower[i].charCodeAt(0) > 'z'.charCodeAt(0)) {
        splitString.push(string.slice(head, i));
        head = i + 1;
      // Split on but retain Capital letters
      else if (string[i] != lower[i]) {
        splitString.push(string.slice(head, i));
        head = i;
    return splitString;

function spinalCase(str) {
  return str
    .split(new CapitalOrNonletterSplit)
    .filter(elem => elem)
1 Like

Thanks a lot for your review! Just check the 3rd solution. That was incredible. My mistake was that I didn’t look through all of the RegEx methods in my notes. Somehow I missed the positive lookaheads and they were the changing point. I was stuck for many hours trying to split the string with no dividers like “HelloThere” and that’s where the lookaheads are helpful.

Guess I need to prepare for the RegEx tasks better because there are a lot of expression methods which are essential to optimize your code.

Once again, thanks for the help!

Regex and “optimize” don’t usually go together. Regex is a very powerful tool, but its also somewhat slow. Its good to know about Regex, but don’t forget about other options available to you.

1 Like

Thanks, didn’t know that regex are slow, learning something new every day!

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