contains duplicate

Question:
Given an array of integers, find if the array contains any duplicates. 
Your function should return true if any value appears at least twice in 
the array, and it should return false if every element is distinct.

Approach

This one is pretty straightforward. Just loop through the array and store the value in a hash. If the value is already in the hash, you return true. return false if it makes it through the loop

Solution

var containsDuplicate = function(nums) {
    var duplicates = {};
    for(var i = 0; i < nums.length; i++) {
        if(duplicates[nums[i]]) {
            return true;
        }else{
            duplicates[nums[i]] = 1;
        }
    }
    return false;
};