find the size of the largest shape.js

/** Algorithm: given a collection (matrix) of
  pixels you must find the size of the largest shape. 
  Shapes were defined as pixels touching each other orthogonality. */
var input = [
  [1, 1, 1, 1, 0],
  [1, 1, 0, 1, 0],
  [1, 1, 0, 0, 0],
  [0, 0, 0, 0, 0]
];
var input2 = [
  [1, 1, 0, 0, 0],
  [1, 1, 0, 0, 0],
  [0, 0, 1, 0, 0],
  [0, 0, 0, 1, 1]
];

console.log(findMax(input));
console.log(findMax(input2));
function findMax(input) {
  var count = 0;
  let rowCount = input.length;
  let colCount = input[0].length;
  for (let i = 0; i < rowCount; i++) {
    for (let j = 0; j < colCount; j++) {
      var currentCount = search(input, i, j, 0);
      if (currentCount > count) {
        count = currentCount;
      }
    }
  }
  return count;
}

function search(input, row, col, counter) {
  if (
    row < 0 ||
    col < 0 ||
    row > input.length - 1 ||
    col > input[0].length - 1 ||
    input[row][col] === 0
  ) {
    return counter;
  } else {
    input[row][col] = 0;
    counter = counter + 1;
  }
  // top, right, bottom, left
  counter = search(input, row - 1, col, counter);
  counter = search(input, row, col + 1, counter);
  counter = search(input, row + 1, col, counter);
  counter = search(input, row, col - 1, counter);
  return counter;
}