Find closest number in ES6

JS: Closest number

const closestNumber = (array, num) => {
  const i = 0;
  let minDiff = 1000;
  let ans;
  
  for (i in array){
   const m = Math.abs(num - array[i]);
   
   if (m < minDiff) { 
      minDiff = m; 
      ans = array[i]; 
    }
  }
    
  return ans;
}

/**
 * Call array name and desired value to be closest
 */ 
const array = ['100', '50'];
console.log(closestNumber(array, 88));