Problem 13/30 of LeetCode 30-day challenge

findMaxLength.js

let findMaxLength = function(nums) {
  const map = new Map();
  map.set(0, -1);
  let count = 0,
      max = 0;
  for(let i = 0; i < nums.length; i++) {
    if(nums[i] === 0){
      count--;
    } else {
      count++;
    }
    
    max = map.has(count) ? Math.max(max, i - map.get(count)) : max;
    if (!map.has(count) || map.has(count) === -1) {
          map.set(count, i);
    }
  }
  return max;
};