Filter over an Array

JavaScript
1

Hey, I’m trying to use the Filter over an Array, but although when debugging it appears to be filtering, the end result is the same original array. Ex below:

let orig_arr = ["A", "A#/Bb", "B", "C", "C#/Db", "D", "D#/Eb", "E", "F", "F#/Gb", "G", "G#/Ab"];
let new_arr = this.orig_arr.filter((elm) => {
if(elm.indexOf("/")!=-1) {
elm = elm.split("/")[0];
}
return tun;
})

What I want is the new_arr to be:

["A", "A#", "B", "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#"];

But it ends like a clone of the orig_arr, eg same elms.

Thanks in advance.

2
  1. You don’t need this
  2. Use proper indenting
  3. tun is not defined? Maybe you wanted to return the direct result of elm.indexOf("/") So there is not even a need to have if. just return elm.indexOf("/") != -1
  4. Or if you want cleaner code: orig_arr.filter(el => !el.includes('/'))
3

By looking closer at your question, I see that filter is not what you want :slight_smile:
In this case you need a .map. You only use filter if you actually want to remove from an array.

Here is the solution:

orig_arr.map(note => note.includes('/') ? note.split('/')[0] : note)

4

Thanks MartinMuzatko for the tip:

Sorry : elm instead of tun

The this is because the code is inside a class, more precisely in a constructor.

I’ll learn about the map method and I’ll try it.

===

Update: map worked perfectly! Thanks for the lesson!!!

5

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