update instance of a class that contains an onclick function

Question

I have a typescript class myClass with an array instance:

module myModule {
    export class myClass {

        arrayElements: Array<string>;

...
}
}

and in this class I have a function myfunction() where I create a button and I handle click event:

function myfunction(){
...
var button = (<HTMLButtonElement>document.createElement("BUTTON"));


            button.onclick = function () {
                // something
            }
...
}

in "something" I'd like to update my array instance (i.e. push a string), but I don't know how. If I try

this.arrayElements.push("example");

When I click on button (in .html page) I have this error :

Uncaught TypeError: Cannot read property 'push' of undefined

most likely because "this" is instance of HTMLButtonElement.

If I try with

myClass.prototype.arrayElements.push("example");

I have the same error. Is there a way to realize my purpose?