Basic Algorithm Scripting - Mutations

[gajulasambhavi7]

Tell us what’s happening:

I wasn’t able to understand, how the commented part works !??
I want some detailed explanation of that line.

Please help!

Your code so far

function mutation(arr) {
  const test = arr[1].toLowerCase();
  const target = arr[0].toLowerCase();
  for (let i = 0; i < test.length; i++) {
    if (target.indexOf(test[i]) < 0) return false;   // < 0  This Line
  }
  return true;
}

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

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Challenge: Basic Algorithm Scripting - Mutations

Link to the challenge:

freeCodeCamp.org

[DDorf]

Hey there,

let’s look at it step by step.

When we call mutation(["hello", "hey"])

const test = arr[1].toLowerCase(); // hey
const target = arr[0].toLowerCase(); // hello
for (let i = 0; i < test.length; i++) {
  if (target.indexOf(test[i]) < 0) {
    return false;
  }
}
return true;

target === 'hello'

when i = 0 => test[0] === 'h'

'hello'.indexOf('h') === 0

when i = 1 => test[1] === 'e'

'hello'.indexOf('e') === 1

when i = 2 => test[2] === 'y'

'hello'.indexOf('y') === -1

When indexOf() cannot find the value it’s looking for, it returns -1.