Finding the Maximum in a Nested Array in JavaScript

Let’s say, we have to write a simple function in JavaScript that takes in the following array of Numbers (nested to any level) −

const arr = [
   15, 24,
   [
       29, 85, 56,
       [
           36, 14, 6, 98, 34, 52
       ],
       22
   ], 87, 60
];

and return the greatest number present in the array.

For example,

If the input array is −

const arr = [
   34, 65, 67,
   [
       43, 76, 87, 23, 56, 7,
       [
           54, 7, 87, 23, 79, 994, 2
       ],
       54
   ], 54, 4, 2
];

Then the output should be −

994

We will use recursion to find the greatest number in the array,

Example

Following is the code −

const arr = [
   34, 65, 67,
      [
         43, 76, 87, 23, 56, 7,
         [
            54, 7, 87, 23, 79, 994, 2
         ],
      54
   ], 54, 4, 2
];
const getGreatest = (arr, greatest = -Infinity) => {
   for(let i = 0; i < arr.length; i++){
      if(Array.isArray(arr[i])){
         return getGreatest(arr[i], greatest);
      };
      if(arr[i] > greatest){
         greatest = arr[i];
      }
   };
   return greatest;
};
console.log(getGreatest(arr));

Output

This will produce the following output in console −

994