# Find the longest sub array of consecutive numbers with a while loop in JavaScript

JavascriptWeb DevelopmentObject Oriented Programming

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We are required to write a function with a while-statement that determines the length of the largest consecutive subarray in an array of positive integers.

For instance −

If the input array is −

const input = [6, 7, 8, 6, 12, 1, 2, 3, 4] --> [1,2,3,4]

Then the output should be −

4

If the input array is −

const input = [5, 6, 1, 8, 9, 7] --> [8,9]

Then the output should be −

2

Therefore, let’s write the code for this function −

## Example

const arr = [6, 7, 8, 6, 12, 1, 2, 3, 4];
const arr1 = [5, 6, 1, 8, 9, 7];
const findLongestSub = arr => {
let count = 1, len = 0, max = 1;
while(len < arr.length){
if(arr[len] === arr[len - 1] + 1){
count++;
if(max < count){
max = count;
}
}else{
count = 1;
};
len++;
};
return max;
};
console.log(findLongestSub(arr));
console.log(findLongestSub(arr1));

## Output

The output in the console will be −

4
2
Updated on 28-Aug-2020 14:05:02