void expression (Definition)

An expression whose value is discarded and is evaluated purely for its side effects.

Example code:

   <HTML>
   <HEAD>
   </HEAD>
   <BODY>
   <SCRIPT>
   function clickMe(aString)
   {
      alert(aString);
   
      return "Some results to be ignored";
   }
   </SCRIPT>
   <A HREF="javascript:clickMe('Test');">Test</A>
   </BODY>
   </HTML>

See also:Constant expression, Conversion

Refer to:

Side effect