example.js

// check to see if one array is in another array.
const arrOne = ["a", "b", "c", "d", "e"]
const arrTwo = [1, "b", 2, 3, 4]
//we want to return true if any elments from array one exist inside array two.

//let define a funtion that can solve this problem

const compare = (arr1, arr2) => {
  let hashMap = {}// set an empty object
for(let i = 0; i < arr1.length; i++){
      if(!hashMap[arr1[i]]){
          hashMap[arr1[i]] = true
      }
  }

for(let j = 0; j < arr2.length; j++){
      if(hashMap[arr2[j]]){
          return true
      }
  }
return false
}

compare(arrOne, arrTwo)
//=> true