How to replace certain symbol in array?

Question

Can you give me a hint what do I wrong trying to replace space symbol (' ') to ('-').

This is my code:

function hypernateAndLowerCase(strings)
{
  let newArray = [];
  for (let i = 0; i < strings.length; i++) { 
    if (strings[i].indexOf(' ')){
       strings[i].replace(' ', '-');

    }

    newArray.push(strings[i].toLowerCase());
  }
  return newArray;
}

console.log(hypernateAndLowerCase(['HELLO WORLD', 'HELLO YOU']));

Answer 1

.replace does not mutate the original string - strings are immutable, so you'd have to explicitly assign the result of using replace for it to work. But, .map is more appropriate here, since you want to transform one array into another:

function hypernateAndLowerCase(strings) {
  return strings.map(string => string.replace(' ', '-').toLowerCase());
}

console.log(hypernateAndLowerCase(['HELLO WORLD', 'HELLO YOU']));

Note that passing a string to .replace will mean that, at most, only one occurrence will be replaced. If you want all occurrences to be replaced, use a global regular expression instead.

Answer 2

You can simplify your function to following

function hypernateAndLowerCase(strings) {
  return strings.map(v => v.replace(/ /g, "-").toLowerCase());
}

console.log(hypernateAndLowerCase(['HELLO WORLD', 'HELLO YOU']));