217 Contain Duplicate.js

// Leetcode #217
// Language: Javascript
// Problem: https://leetcode.com/problems/contains-duplicate/
// Author: Chihung Yu
/**
 * @param {number[]} nums
 * @return {boolean}
 */
var containsDuplicate = function(nums) {
    if(nums === null){
        return false;
    }
    
    var map = {};
    
    for(var i = 0; i < nums.length; i++){
        var val = nums[i];
        if(map[val]){
            return true;
        } else {
            map[val] = true;
        }
    }
    
    return false;
};