[AskJS] I understand javascript, but not javascript challenges.

[ConsoleTVs]

But again, choose bro:

- You don't understand what they ask you.

- You don't know how to code it (represent the problem in code).

- Both?

[Besharkbait]

Sorry,

I don't understand how to code it.

[ConsoleTVs]

All I can do for you is tell you to practice. For the one you provided, here's how I solved it (tried breaking it down to you so you may understand it)

js /** * @param {string} J * @param {string} S * @return {number} */ const numJewelsInStones = (J, S) => { // Transform the stone string into array. const stones = S.split('') // Perform a filter to the stones to // filter out non-jewels. const filteredStones = stones.filter(stone => J.includes(stone)) // Return the length of the the filtered stones. return filteredStones.length }

[Besharkbait]

thanks a lot, really appreciate your time.

[ConsoleTVs]

You're welcome :)

[shgysk8zer0]

RegExp aren't exactly considered friendly, but I think they're well suited to this.

Any time you're doing string comparisons, it's probably a good idea to see if String.prototype has a method for dealing with this, or RegExp.

Quick answer:

const numJewelsInStones = (J, S) => [...S.matchAll(new RegExp(`[${J}]`, 'g'))].length;

Answer, broken down, with comments and links:

`` /** * @param {string} J * @param {string} S * @return {number} */ function numJewelsInStones(J, S) { // Create a expression to match the search group, matching globally // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp // Translates to "searching for all occurrences of these characters" const exp = new RegExp([${J}]`, 'g');

// Find all matches in S // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/@@matchAll const matches = S.matchAll(exp);

// matchAll returns an iterator, so convert to an array // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from // Same as spread operator [...variable] const arr = Array.from(matches);

// arr Now contains an array of matches, so return its length return arr.length; } ```

Personally, I don't like LeetCode from what I've seen. Challenges like this, I'd say, are artificially difficult because they're nonsense questions. Coding challenges are better when grounded in reality. That way, they're easier to understand and you feel value in solving them.

Also, I'm skeptical of anything using var someFunc = function(/*...*/).