binarySearch.ts

// input is an ordered array
let input_1 = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J']

// we pick a random value from the input array
let randomValue = input_1[Math.floor(Math.random() * input_1.length)];

let binaryGuessIndex = (sortedArray:any[]): number => Math.floor(sortedArray.length/2)

function search (sortedArray:any[], value:any): any {

  let guessIndex = binaryGuessIndex(sortedArray);
  let guess = sortedArray[guessIndex]

  if (value < guess) {
    guess = search(sortedArray.slice(0,guessIndex), value);
    return guess;
  }
  if (value > guess) {
    guess = search(sortedArray.slice(guessIndex+1, sortedArray.length), value);
    return guess
  }
  if (value == guess) {
    return guess;
  }
}

console.log(search(input_1, randomValue));