Instantiating a javascript object and populating its properties in a single line

Why don't you just do it this way:

var obj = {"city": "A", "town": "B"};

Like so:

var obj = {
    city: "a",
    town: "b"
}

function MyObject(params) {
    // Your constructor
    this.init(params);
}

MyObject.prototype = {
    init: function(params) {
        // Your code called by constructor
    }
}

var objectInstance = new MyObject(params);

This would be the prototype way, which i prefere over plain object literals when i need more then one instance of the object.