array-diff.js

/**
Developer comment
- This is a difference function, which subtracts one list from another and returns the result.
- we'll go over all 'b' values
- we'll use filter to knock down each of 'b' values from 'a' array
**/

function arrayDiff(a, b) {
  let newArray = a;

  if(a.length === 0 || b.length === 0){
    return a || []
  }
  
  b.map((val) => {
    newArray = newArray.filter((aValue) => aValue !== val);
  });
  
  return newArray;
}