The MouseDown event is triggered when the user presses a mouse button.
The MouseUp event is triggered when the user releases a mouse button.
The button label is stored in the document.formname.fieldname.value property where the formname is replaced by name defined in the <form> tag‚ and the fieldname is replaced by name defined in the <input> tag for a particular button. The value property can be replaced by the value defined in the <input> tag or assigned in the function.
Adapted from: