532. K-diff Pairs in an Array.js

var findPairs = function(nums, k) {
    if (nums.length === 0 || k < 0) {
        return 0;
    }
    var dict = {};
    var count = 0;

    for (var i = 0; i < nums.length; i++) {
        var number = nums[i];
        dict[number] = (dict[number] === undefined) ? 1 : dict[number] += dict[number];
    }
    for (var numb in dict) {
        numb = parseInt(numb);
        if (k === 0) {
            if (dict[numb] > 1) {
                count++;
            }
        } else if (dict[numb + k] !== undefined) {
            count++;
        }
    }
    return count;
};