listen to click event JS

Question

I tried to listen to click event in Haxe/JS:

static function main()
{
    var initHandler:Dynamic = init;        
    Browser.window.onload = initHandler;
}

static private function init()
{
    var clickHandler:Dynamic = learnBtn;    
    Browser.document.getElementById("readMoreBtn").addEventListener("click", clickHandler);
}

static private function learnBtn()
{
}

I'm really need all this?

Why i can't do this (without initHandler and clickHandler):

Browser.window.onload = init;

OR

Browser.document.getElementById("readMoreBtn").addEventListener("click", learnBtn);

2. The JS file not loaded after all the HTML? I can to define that?

3. It's not related to this topic but I tried to google and search in Haxe.org but nothing. what it is "untyped" keyword.

Answer 1

Using a Dynamic intermediary variable indirectly solves your problem but you should try understanding the compiler error message.

What the compiler says:

If you write:

function init() {
   // do stuff on window.onload
}

Browser.window.onload = init;

the compiler will tell you:

Test.hx:22: characters 68-117 : Void -> Void should be js.html.EventListener
Test.hx:22: characters 68-117 : Void -> Void should be Dynamic -> Void

What does that mean? It means that your function init(), which has a Void->Void signature, should be js.html.EventListener, which is defined as Dynamic->Void.

The right code:

In other words you init() function should have an argument so it should be declared as:

function init(event:Dynamic) {
   // do stuff on window.onload
}

Forcing the compiler

You can tell the compiler to let you write possibly incorrect (but we know valid) code:

var foo:Dynamic = init;
Browser.window.onload = foo; // always happy

Browser.window.onload = untyped init; // do not type, please

Browser.window.onload = cast init; // I'm sure I'm right