只允许button和a 标签点击一次

==========<A>=============

<script>

    $("a").click(function(){
$(this).css("color","#CCC");
$(this).unbind("click");
form.submit();     
    })

</script>

=========<button>==============

<button id="btn" disabled="disabled">确定</button>


<script>    $("#btn").attr("disabled","true");    


$("#btn").attr("disabled","disabled");    


$("#btn").attr("disabled","false");    


$("#btn").removeAttr("disabled","disabled");


</script>