onmousedown (HTML attribute)

Depr. Version
Browser support (more…)
IE5.5+ FF1+ SA1.3+ OP9.2+
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The onmousedown attribute is similar to the onclick attribute, but differs in that the event is triggered the moment the mouse button is pressed on the element, rather than at the point at which the mouse button is released (onclick is effectively a combination of onmousedown and onmouseup event on the element in question). This event isn’t often seen in practice, possibly because it can so easily cause events to be triggered accidentally. If you’re using an onclick event, the user can move the cursor off the element, release the mouse button, and avoid triggering the action if it was an accidental button press; this is not the case with onmousedown.

Note that this event attribute cannot be applied to the following elements:

  • applet
  • base
  • basefont
  • bdo
  • br
  • font
  • frame
  • frameset
  • head
  • html
  • iframe
  • isindex
  • meta
  • param
  • script
  • style
  • title


The event handler for the onmousedown event calls the function highlightThis:

<div onmousedown="highlightThis();">Holiday dates for 2008</div>


This attribute has no fixed value. It’s up to the author to decide on the scripting that’s included here, be that a call to one or more defined functions, or a simple alert() statement.


Internet Explorer Firefox Safari Opera
5.5 6.0 7.0 1.0 1.5 2.0 1.3 2.0 3.0 9.2 9.5
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Every browser listed supports this attribute. However, inline event handlers such as this should be avoided. In the same way that inline CSS styles are frowned upon but externally defined CSS styles are considered good practice, inline event handlers should be stripped out and replaced with events attached unobtrusively through the DOM.

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