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Editorial Team
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Asked: 2026-06-11T16:59:18+00:00

Following this question I have recently asked : Understanding Document.createElement() Here is the context

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Following this question I have recently asked : Understanding Document.createElement()

Here is the context :

  • There is a text-zone in my GWT GUI that holds a text
  • Users can select a word (or a sequence of words) in this text-zone and transform it / them into a highlighted text
  • highlighted texts need to be able to listen to users : click, right-click, dragging & dropping operations
  • A scenario with 1000 highlighted text in the text-zone is not impossible.

I was wondering :

  1. Is it a bad approach to manipulate DOM elements directly in GWT ? (Without using Widgets)
  2. Is it a bad approach to do things like that Add listener to SpanElement ? Can it cause memory leaks ?
  3. What is the best approach to achieve such things ? I’ve done some tests with a simple custom widget that uses a span element, and adding 1000 widgets to the RootPanel takes approximatively 6 to 10 seconds in DevMode. When I use DOM elements direclty, this operation duration goes under 1 second (even less than 200ms with optimizations).

EDIT

Performance should not be a problem, according to some real tests I did after @Gilberto advices. http://jmichelgarciagwt.appspot.com/DOMTesting.html

Still, I would love to have feedbacks for questions 1) and 2)

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1 Answer

  1. Editorial Team

    Adding listeners/handlers to hundreds of span elements/widgets is definitely a bad approach.

    If you stay with GWT, you can attach a single event handler to your “text zone” widget, and then find which element has been the source of the click:
    http://comments.gmane.org/gmane.org.google.gwt/61911

    If you go with DOM elements, you can attach a single event listener to your “text zone” element and find out the event source when it bubbles to it. For example:
    http://icant.co.uk/sandbox/eventdelegation/

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