Finding letters in 2nd array element in 1st array element

Question

Using javascript, I want to check if the string in the 1st array element contains all the letters of the 2nd array element. If so, return true. E.g. ["Mary", "Aarmy"] => true; ["hello", "hey"] => false.

I've tried the following code, which works for ["Mary", "Aarmy"] and ["voodoo", "no"], but doesn't work for ["hello", "hey"]. Appreciate any help, thanks!

function mutation(arr){
var str1 = arr.pop().toLowerCase();
 var str2 = arr.pop().toLowerCase();
 for(var i = 0; i < str2.length; i++){
  if(str1.indexOf(str2[i]) !== -1){
    return true;
  }
    else return false;
 }
} 

Answer 1

When you use pop() it'll return the last element in the array and not the first.

Also your if else is inside for and has a return statement. This does not let the for loop run completely and returns after the very first loop.

function mutation(arr){
 var str2 = arr.pop().toLowerCase();
 var str1 = arr.pop().toLowerCase();
 console.log("str1: " + str1);
 console.log("str2: " + str2);
 for(var i = 0; i < str2.length; i++){
  if(str1.indexOf(str2[i]) === -1){
    return false;
  }
 }
 return true;
}

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

arr = ["Mary", "Aarmy"];
console.log(mutation(arr));

Answer 2

Considering you can use Set, and lodash, here is another solution:

const _ = require("lodash");

function mutation(arr) {

  var set1 = new Set(arr.pop().toLowerCase().split(''));
  var set2 = new Set(arr.pop().toLowerCase().split(''));

  return _.isEqual(set1, set2);

}

console.log(mutation(["Mary", "Aarmy"])); //true
console.log(mutation(["hello", "hey"])); //false
console.log(mutation(["voodoo", "no"])); //false

Check the working sample: https://jsfiddle.net/sayan751/3q8rtqy3/