In newer browsers, when you start dragging an image, a default behaviour is triggered, so you can drag the image ex. to the desktop or whereever you want. Firefox, Opera, and Chrome does this, and also Internet Explorer 8. As anyone could guess, problems start with the latter.

I wanted to create a solution where the user can drag and drop objects around, and of course in this case it is not allright when the browser overrides my event handlers with its default one.

In standards-compliant browsers the solution is easy, the Event object has a method called preventDefault(), and when you call it in the 'onmousedown' event handler, this default behaviour is cancelled. I was not really surprised when it was only IE8 where it did not work. Well, in IE the Event object has no preventDefault() method, IE uses a boolean property called returnValue. I tried that one, nothing changed.

I spent some time googling about this, no results. Then in MSDN I found out that IE has a special event, called 'ondragstart' , and I already knew that this is the solution (Safari seems to support this event too). So in an 'ondragstart' event handler you have to set returnValue to false, and you are done.

Sometimes very useful to change the properties of a website element when an event occurs. The key is the style member of the object.

A lot of times you might run into using this bloody Javascript function. For example when you are replacing target="_blank"-s for the sake of XHTML Strict valid markup (like in Varga Bence's solution - Hungarian). Not like on this blog site, which is HTML 4 Transitional.

Here is the way it is to be used.

window.open(URL, WindowName[, WindowFeatures]);

Not much to say about URL (well, it is a string and it can be blank). You can use WindowName (string) to refer to the window later, also if you call window.open with the same WindowName several times, it will open a new window only for the first time and use the same window for the other calls.

WindowFeatures (string, format: "featurex=n, featurey=m, ...", I only list those that are widely supported):

• status: displays status bar if 1, does not if 0
• toolbar: displays browser toolbar (Back, Forward, etc.) if 1, does not if 0
• location: displays location field (where you enter the URL) if 1, does not if 0
• menubar: displays browser menu bar if 1, does not if 0
• directories: displays directory buttons (like annoying What's New and What's Cool) if 1, does not if 0
• resizable: window is resizable if 1, is not if 0
• scrollbars: no scrollbars if 0, scrollbars when needed if 1
• height, width: window dimensions in pixels

The WindowFeatures you do not specify will follow the default browser behavior (if you do not specify any, a standard window is opened).

The function returns an object reference which you can pass to a variable and use it to refer the window later (move the window, write to the window, etc.).

var makimajom=window.open("", "bazevaze");
makimajon.moveTo(100, 50);
makimajom.document.write("mennyafrancba");

Mozilla Reference - here you can also find a nice list about which WindowFeatures are supported in certain browsers

Microsoft Reference