neutrino-count-occurence

// Write a program that finds the most frequent number in an array.
// Example: {4, 1, 1, 4, 2, 3, 4, 4, 1, 2, 4, 9, 3} -> 4 (5 times)
function mostFreqNum(arr) {
    var count = {};
    var maxKey = arr[0];
    var i, key;
    for (i = 0; i < arr.length; i++) {
        key = arr[i];
        if (count[key] == undefined) count[key] = 1;
        else count[key]++;
        if (count[key] > count[maxKey]) maxKey = key;
    }
    console.log(arr);
    console.log("Most frequent number: %d (%d times)", maxKey, count[maxKey]);
}
mostFreqNum([4, 1, 1, 4, 2, 3, 4, 4, 1, 2, 4, 9, 3]);