Clean Method to Normalize Javascript Object Properties

Question

I have an array of javascript objects that represent users, like so: ``` [ { userName: "Michael", city: "Boston" }, { userName: "Thomas", state: "California", phone: "555-5555" }, { userName: "Kathrine", phone: "444-4444" } ] ``` Some of the objects contain some properties but not others. What I need is a clean way to ensure ALL objects get the same properties. If they don't exist, I want them to have an empty string value, like so: ``` [ { userName: "Michael", city: "Boston", state: "", phone: "" }, { userName: "Thomas", city: "", state: "California", phone: "555-5555" }, { userName: "Kathrine", city: "", state: "", phone: "444-4444" } ] ``` Update I should have been a little more specific. I was looking for an option that would handle this situation dynamically, so I don't have to know the properties ahead of time. For jQuery specific, the `$.extend()` option is a good one, but will only work if you know ALL the properties ahead of time. A few have mentioned that this should probabl…

Accepted Answer

Since you are using jQuery you can abuse $.extend

```
function Person(options){
    return $.extend({
         userName:"",
         city: "",
         state:"",
         phone: ""
    },options);
}

$.map([{}],Person)
```

update

Heres a way to have dynamic default properties

```
function mapDefaults(arr){
    var defaultProperties = {}
    for(var i =0; i < arr.length; i++){ 
        $.each(arr[i],function(key){
            defaultProperties[key] = "";
        });
    }
    function Defaulter(obj){
        return $.extend({},defaultProperties,obj);
    }
    return $.map(arr, Defaulter);
}

mapDefaults([{a:"valA"},{b:"valB"}]);
/* produces:
 [{a:"valA",b:""},{a:"",b:"valB"}]
*/
```

Clean Method to Normalize Javascript Object Properties

Solution

Problem