esempio:ciaocodice:<html> <head> <script language="javascript"> function allChk(objForm,on_off){ for (nn=0;nn<objForm.length;nn++) { el = objForm.elements[nn]; if (el.type=="checkbox") el.checked=on_off; } } </script> </head> <body> <form name="FormName" action="" method="get"> <input type="checkbox" value="checkbox1" name="r1"> <input type="checkbox" value="checkbox2" name="r2"> <input type="checkbox" value="checkbox3" name="r3"> <input type="checkbox" value="checkbox4" name="r4"> <input type="checkbox" value="checkbox5" name="r5"> <input type="button" value="on" onclick="allChk(this.form,true)"> <input type="button" value="off" onclick="allChk(this.form,false)"> </form> </body> </html>