Finding both characters and putting them in a new array

I’ve created a function that passes in a string and a character. The string is saturday and the character is a.

I want the result to be an array that contains all the index numbers of where the letter ‘a’ sits in saturday.

Then array ends up with only [1]. So it finds the first a sitting at the second index. I tested this by changing saturday to soturday and the console prints the array with [6].

I want the result to be [1, 6]

I’ve tried putting the return result outside the next set of {} braces but no joy.

const subLength = (str, cha) => {
  let result = [];

  for (let i = 0; i < str.length; i++) {

    if (str.charAt(i) === cha) {
      result.push(str.indexOf(cha));

      return result;
    }
  }

};
console.log(subLength('Saturday', 'a'));

>Solution :

You are pretty close.

In your code the return is being executed as soon as a match is found. You want to return after you’ve checked every char – so I’ve moved it after the foreach.
indexof has a second parm, which defines the char to start looking from. If you omit it, you will get the index of the first match every time – which is not what you want.

const subLength = (str, cha) => {
  let result = [];
  
  for(let i = 0; i < str.length; i++){
    if(str[i] === cha) {
      result.push(str.indexOf(cha, i));
    }
  }
  return result;
};
console.log(subLength('Saturday', 'a'));

Room for improvement

Since you are iterating over every char anyways, you can simply store every i where str[i] matches cha.

So optimized:

const subLength = (str, cha) => {
  let result = [];
  
  for(let i = 0; i < str.length; i++){
    if(str[i] === cha) {
      result.push(i);
    }
  }
  return result;
};
console.log(subLength('Saturday', 'a'));

An even simpler version using regex:

const subLength = (str, cha) => {
  return [...str.matchAll(new RegExp(cha, 'g'))].map(e => e.index);
};
console.log(subLength('Saturday', 'a'));