Automatically create object if undefined

Question

Is there an easy way to automatically add properties to objects if they don\'t allready exist?

Consider the following example:

var test = {}
test.hel         


        

Answer 1

You won't be able to do this without some sort of function, as JavaScript doesn't have a generic getter/setter method for objects (Python, for example, has __getattr__). Here's one way to do it:

function add_property(object, key, value) {
    var keys = key.split('.');

    while (keys.length > 1) {
        var k = keys.shift();

        if (!object.hasOwnProperty(k)) {
            object[k] = {};
        }

        object = object[k];
    }

    object[keys[0]] = value;
}

If you really want to, you could add it to the prototype of Object. You can call it like so:

> var o = {}
> add_property(o, 'foo.bar.baz', 12)
> o.foo.bar.baz
12