binarySearch.js

function isExist(target, array) {
  let sorted = array.sort((a, b) => a - b);  
  let midPoint = Math.floor(sorted.length / 2);

  if (sorted[midPoint] === target) {
    console.log('exist');
  } else if (sorted.length <= 1) {
    console.log('not exist');
  } else if (sorted[midPoint] < target) {
    isExist(target, sorted.slice(midPoint, sorted.length));
  } else if (sorted[midPoint] > target) {
    isExist(target, sorted.slice(0, midPoint));
  }
}