Mutations-want to solve using if-else condition

Tell us what’s happening:
For solving this problem can I use if else condition and satisfy all the cases? Please tell me I need help.

Your code so far

function mutation(arr) {
  var newArray=[];
   for(var i=0;i<arr.length;i++)
     {
       newArray.push(arr[i].toLowerCase());
     }
  
  
      if(newArray[0].indexOf(newArray[1]))
      {
        return true;
      }


    else if(newArray[0]!==newArray[1])
      {
        return false;
      }

  
}

mutation(["hello", "Hello"]);

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Link to the challenge:

I am not sure what all of the test cases are and I am seeing that your mutation() function is lowercasing both string values and then comparing them, once with an interesting way of using indexOf(). I think that condition will always return a false, being that 0 or -1 are the two possible returned values and which both return “falsey” in an if() condition.
For info on indexOf() https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf
For info on conditionals https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/if...else