Mutation

function mutation(arr)
{
    // turn the elements lower case to ignore case, and split into characters
    var str1 = arr[0].toLowerCase().split("");
    var str2 = arr[1].toLowerCase().split("");
    // loop through the second first since all letters there must be present in first
    for (var i=0; i<str2.length; i++)
    {
        // flagging a match
        var match=false;
        for (var j=0; j<str1.length; j++)
        {
            if(str1[j]==str2[i])
            {
                match=true;
            }
        }
        // if a match wasn't found, then this should return false (breaking the function loop)
        if (!match) return false;
    }
    return true;
}

mutation(["hello", "hey"])