Improving website performance: removing outdated header contributions and implementing AJAX panel updates

Question

Improving website performance: removing outdated header contributions and implementing AJAX panel updates

We are developing a Wicket application with heavy use of AJAX, and we've encountered an issue with panels contributing CSS via the renderHead() method. The problem arises when panels are replaced using AJAX functions, such as an AjaxTabbedPanel, as the header contributions from the old panels remain in the application and cause conflicts. This not only leads to response bloat but also causes rendering issues in other parts of the application when CSS declarations are too generic.

Is there a solution to this problem? Perhaps a way to recreate the IHeaderResponse when a panel is replaced or no longer visible?

Below is an example of how our header contributor is implemented:

@Override
public void renderHead(IHeaderResponse response) {
    response.renderCSSReference(new SharedResourceReference(SearchMainPanel.class, "Search.css"));
}

We are using Wicket 1.5.3.

Although I have managed to address this issue by including a custom label that renders a

<link rel="stylesheet" ... />

in the Panel's body markup instead of using header contributors, we faced compatibility problems with IE8 not recognizing the presence of this CSS. Therefore, we need to reconsider our approach.

css ajax wicket wicket-1.5

Answer 1

Answer №1

When handling an Ajax request, each AjaxRequestTarget will be assigned a new IHeaderResponse specifically for that particular request. The issue you are encountering is likely due to a previous request including a stylesheet that should no longer be present on the page. To solve this problem, you must re-render the page without that specific file in order for the browser to ignore it.

For initial rendering of each tab, you can rely on cascading styles because Wicket will load the corresponding stylesheet when rendering the Panel for the first time. However, if you revisit a tab (Panel) that has already been rendered, Wicket will not re-load the stylesheet as it was already loaded, thus requiring a workaround to handle cascading styles limitations.

To address this challenge, the recommended approach is to namespace your styles. This involves wrapping each panel in a tag with a unique namespace class (e.g. "tab1") and defining all styles based on that class:

.tab1 .heading {
    font-weight: bold;
}

.tab1 .description {
    background: blue;
}

.tab2 .heading {
    font-size: 1.3em;
}

.tab2 .description {
    background: lightblue;
}

By using namespaced selectors for styling, you can differentiate between individual tab styles and ensure that any necessary cascading effects still function correctly.

Answer 2

When handling an Ajax request, each AjaxRequestTarget will be assigned a new IHeaderResponse specifically for that particular request. The issue you are encountering is likely due to a previous request including a stylesheet that should no longer be present on the page. To solve this problem, you must re-render the page without that specific file in order for the browser to ignore it.

For initial rendering of each tab, you can rely on cascading styles because Wicket will load the corresponding stylesheet when rendering the Panel for the first time. However, if you revisit a tab (Panel) that has already been rendered, Wicket will not re-load the stylesheet as it was already loaded, thus requiring a workaround to handle cascading styles limitations.

To address this challenge, the recommended approach is to namespace your styles. This involves wrapping each panel in a tag with a unique namespace class (e.g. "tab1") and defining all styles based on that class:

.tab1 .heading {
    font-weight: bold;
}

.tab1 .description {
    background: blue;
}

.tab2 .heading {
    font-size: 1.3em;
}

.tab2 .description {
    background: lightblue;
}

By using namespaced selectors for styling, you can differentiate between individual tab styles and ensure that any necessary cascading effects still function correctly.

Improving website performance: removing outdated header contributions and implementing AJAX panel updates

Answer №1

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