Mutations test help

var a =['hello', 'her'];
a[1] = a[1].toLowerCase();
a[0] = a[0].toLowerCase();
var l= a[1].length;


for (i=0;i<l;i++){
  n= a[0].indexOf(a[1][0]);
  if (n<0)
    {break;
    }
}
if (n!=-1){
  console.log(true);
}
else {
  console.log(false);
}

the outcome is true, instead of false. could someone show me where i am getting it wrong. thanks

problem area:
n= a[0].indexOf(a[1][0]);

a[1][0], will always return 1 character ,‘h’, no matter which index the for loop is at, find a way to make that a variable and it will work