Implement the Mutations Algorithm

JavaScript
1

Tell us what’s happening:

There’s an error in the console that say’s “TypeError: “i” is read-only” but I don’t see where it’s trying to change i other than in the loop declaration.

Your code so far

function mutation (genes) {
  // Sep stands for seperated, I did this for the alphabet test.
  let genesSep = genes[1].split("");
  // Len stands for length to check if all characters and in the first string
  let correctLen = 0;
  console.log(genesSep);
  for (const i = 0; i < genesSep.length; i++) {
    console.log(i)
    if (genes[0].toLowerCase().includes(genesSep[i].toLowerCase())) {
      correctLen++;
      // To check if all characters are in the second string.
      if (correctLen.length == genesSep.length) {
        return true;
      }
    } else {
      return false;
    }
  }
  
}

console.log(mutation(["hello", "hey"]));

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/143.0.0.0 Safari/537.36 Edg/143.0.0.0

Challenge Information:

Implement the Mutations Algorithm - Implement the Mutations Algorithm

2

But in your loop, you’ve declared i as a constant. Can you change the value of a constant?

3

why would a loop be a an exception?

4

No it can’t be changed.

The thing I can’t figure out is where I’m trying to change it, if I remember right, it makes an exception for the declaration (not sure if that’s the right word, what I mean when I say that is the part after “for“:

).

And to answer @ILM ‘s question, I don’t actually know, I just thought it said that in one of the theory documents.

5

here you are changing i

also you are thinking of for of and for in loops, they behave differently from for loops

6

So that does apply, but not to this kind of loop?

7

you can do for (const word of words) because each const word is in a different scope

the scopes in a for loop work differently and the i is always the same variable, so you are doing const i = 0; i++ which you can’t do

1 Like
8

Ok, that solved the problem, thank you.

9

That fixed the first test but I am having problems with the other ones.

It is reaching the full length and I’m using .toLowerCase so I don’t know why it’s not returning true.

10 
console.log(`CL: ${genesSep.length} ?CL: ${correctLen}`);
      // To check if all characters are in the second string.
      if (correctLen.length == genesSep.length) {

What you print here is not what you are checking

1 Like
11

How so? They’re in a different order but it’s the same thing isn’t it?

12

Oh I see, it’s because in the If statement it’s checking correctLen.length instead of correctLen.

1 Like