MissingInteger 100% Solution in Javascript

Question

app.codility.com

My Solution

app.codility.com

function solution(A) {
    
    let count = [];
    let minMissing = 0;
    
    for (let i = 0; i < A.length; i++) {
        if (A[i] > 0) {
            if (count[A[i]] === undefined) {
                count[A[i]] = 1;
            } 
            
            while (count[minMissing+1] != undefined) {
                minMissing++;
            }
        }
    }
    
    return minMissing+1;
    
}