In GWT, Adding An Event Handler On Any Of The Host Page Tags

I want to add a MouseOver event handler for any tag. Let say just for the example, that I want to add the event handler for every anchor page in a legacy HTML page. Following the G

Solution 1:

You'll probably want to use Document.getElementsByTagName("a"), which returns a NodeList containing the elements, which can be cast to AnchorElements exposing the tag's href attribute.

Try this code:

NodeList<Element> elems = Document.get().getElementsByTagName("a");
for (int i = 0; i < elems.getLength(); i++) {
  Element elem = elems.getItem(i);
  AnchorElement a = AnchorElement.as(elem);
  if (!a.getHref().startsWith("http://yoursite.com")) {
    a.setHref("http://yoursite.com/blockedpage");
  }
}

To add an event handler, you can instead wrap the Element in an Anchor using wrap()

for (int i = 0; i < elems.getLength(); i++) {
  Element elem = elems.get(i);
  Anchor a = Anchor.wrap(elem);
  a.addClickHandler(new ClickHandler() {
    @Override
    public void onClick(ClickEvent event) {
      Window.alert("yay!");
    }
  });
}

(If the handler will always do the same thing, you'll want to only instantiate one ClickHandler and add it to each element instead of creating a handler for each element)