Javascript: adjacent Elements Product algorithm

I’m trying to solve a basic javascript algorithm and i’m kinda stuck, here is the question:

Given an array of integers, find the pair of adjacent elements that has the largest product and return that product.

Example

For inputArray = [3, 6, -2, -5, 7, 3], the output should be adjacentElementsProduct(inputArray) = 21.

7 and 3 produce the largest product.

Here is my code, i can’t find the problem but in the tests it says that it returns null:

    function adjacentElementsProduct(inputArray) {
    var cb;
    for(var i=0;i<inputArray.length;i++){
      if(inputArray[i] !== inputArray[inputArray.length-1]){
        if(inputArray[i]*inputArray[i+1] > cb){
          cb = inputArray[i]*inputArray[i+1];
        }
      }
    }
  return cb;
  }

What is my problem and what i need to change?

Answer

The problem with your code is you never initialized cb. So the comparison with cb is always invalid. Here is the correct version of your code –

function adjacentElementsProduct(inputArray) {
    var cb = Number.NEGATIVE_INFINITY;
    for(var i=0;i<inputArray.length-1;i++){
        if(inputArray[i]*inputArray[i+1] > cb){
          cb = inputArray[i]*inputArray[i+1];
        }
    }
  return cb;
}

console.log(adjacentElementsProduct([3, 6, -2, -5, 7, 7]))