JavaScript interview questions [with solutions]

I have been a software engineer for almost 5 years now but (for one reason or another) only today for the first time I interviewed another developer for a position in my company.

Here is the simple exercise that I asked the (junior) candidate to solve:

Write a function that given 2 arrays of characters returns
whether the 2 arrays contain an acronym.

  Eg.

  [ 'b', 'i', 'n', 'a', 'r', 'y' ]
  [ 'b', 'r', 'a', 'i', 'n', 'y' ]
  => TRUE

  [ 'b', 'o', 'a', 't' ]
  [ 't', 'a', 'b', 'o', 'o' ]
   => FALSE

Here are a couple of simple solutions:

Solution 1:

var isAcronym = () => {
    if (!arr1.length || arr1.length != arr2.length) return false;
    arr1.forEach((el) => {
     const id = arr2.indexOf(el);
     if (id == -1) return false;
     arr2[id] = null;
    });
    return arr2.filter(el => !!el).length === 0;
}

var arr1 = ['b','a','g','r','e','i','e','l'];
var arr2 = ['g','a','b','r','i','e','l','e'];

console.log('Is Acronym: ', isAcronym(arr1, arr2));

• Complexity: O(N)
• Optimization: length check, best case: O(1)
• Spatial complexity: in loco

Solution 2:

var isAcronym = () => {
    if (!arr1.length || arr1.length != arr2.length) return false;
    const count = {};
    arr1.forEach(el => {
     if (count[el]) count[el] += 1;
     else count[el] = 1;
    });
    arr2.forEach(el => {
     count[el] -= 1;
    });
    return Object.values(count).filter(res => res !== 0).length === 0;
};

var arr1 = ['g','a','b','i','r','e','l','e'];
var arr2 = ['g','a','b','r','i','e','l','e'];

console.log('Is Acronym: ', isAcronym(arr1, arr2));

• Complexity: O(N)
• Optimization: length check, best case: O(1)
• Spatial complexity: O(N)

Did I miss any bugs? =)