check the exam.js

// The first input array is the key to the correct answers to an exam, like ["a", "a", "b", "d"]. The second one contains a student's submitted answers.

// The two arrays are not empty and are the same length. Return the score for this array of answers, giving +4 for each correct answer, -1 for each incorrect answer, and +0 for each blank answer, represented as an empty string (in C the space character is used).

// If the score < 0, return 0.

// For example:

// checkExam(["a", "a", "b", "b"], ["a", "c", "b", "d"]) → 6
// checkExam(["a", "a", "c", "b"], ["a", "a", "b",  ""]) → 7
// checkExam(["a", "a", "b", "c"], ["a", "a", "b", "c"]) → 16
// checkExam(["b", "c", "b", "a"], ["",  "a", "a", "c"]) → 0

function checkExam(array1, array2) {
    console.log(array1, array2)
    let score = 0
    for (let i = 0; i < array1.length; i++) {
      if (array1[i] == array2[i]) score += 4
      else if (array2[i] != '') score -= 1
    }
    console.log(score)
    return score>=0? score: 0
  }