# Finding a greatest number in a nested array in JavaScript

We have to write a simple function in JavaScript that takes in an array of Numbers (nested to any level) 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, 314, 2
],
54
], 54, 4, 2
];

Then the output should be −

314

We will use recursion to find the greatest number in the array. Let’s write the code for it

## Example

const arr = [
34, 65, 67,
[
43, 76, 87, 23, 56, 7,
[
54, 7, 87, 23, 79, 314, 2
],
54
], 54, 4, 2
];
const findGreatest = (arr, greatest = -Infinity) => {
for(let i = 0; i < arr.length; i++){
if(Array.isArray(arr[i])){
return findGreatest(arr[i], greatest);
};
if(arr[i] > greatest){
greatest = arr[i];
}
};
return greatest;
};
console.log(findGreatest(arr));

## Output

The output in the console will be −

314

Updated on: 26-Aug-2020

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