Nov 28 2009

JavaScript – events with parameters

Frank

If you use JavaScript to put some dynamic to your websites you often have the problem to pass parameters to the event-function. One solution is to use closures. With the element of closures you can access outer variables from inner inline functions.
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Nov 6 2009

Preloading Images with JavaScript

Frank

Sometimes in a complex javascript-application you want to display an image when it is fully loaded. Until then you want to show for example a common loading-imageAjax Loading Image. In this case the best solution is to load the image in background, and then show it to the use. For that you can use the Image-Class provided by the browsers.

This class is the used Class at img-Tags. So you have all known properties, like “src”. With the onload-Event you can then check, if the image was fully loaded or not. An example would be:

?View Code JAVASCRIPT
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var image = new Image();
$(image).load(function () { alert("picture is fully loaded."); });
image.src="http://www.javahelp.info/wp-content/uploads/2009/11/Bild-80-300x64.png";

In the example I use JQuery for event-handling, because this is more comfortable as the normal event-method of JavaScript.