Unable to add key-value pair in Javascript Object after sorting them

Question

Hey I have an object as

data = { vaibhavs:243 "132" , 
         vaibhavs:918 "342", 
         karthikp:265 "345",
         marimuthu:848 "asjkd",
         ushas:918 "sdf15",
         apoorvg:728 "wddfs"....
       }

I need to sort it on the basis of key ,i.e., "vaibhavs:243" alphabatically. I have written the following code for it. I am able to sort the keys, but not able to put it back in the returning object. Please guide what to do.

function sortData(data) {
    var sorted = [];
    Object.keys(data).sort(function (a, b) {
        return a < b ? -1 : 1
    }).forEach(function (key) {
        var obj = {};
        obj[key] = data[key]
        sorted.push(obj);
    });
    return sorted;
}

This is giving me an array of object which i don't want. I want a single object. I can't do this using an array because I need the sorted key-value pairs.

If I am using the following code,

function sortData(data) {
        var sorted = {};
        Object.keys(data).sort(function (a, b) {
            return a < b ? -1 : 1
        }).forEach(function (key) {
            sorted[key] = key[data]
        });
        return sorted;
    }

The above code is always overwriting the existing value. Can someone suggest me how to add the Key value pair. As I have that in sorted order, but just unable to add them in a single object.