html实现网站全局按钮点击后置灰，不允许连续点击

<script>
    document.addEventListener("mouseup", upHandler, true);
    function upHandler(e){
        var target=undefined;
        //元素类型即BUTTON
        if(e.target.tagName=='BUTTON'||(e.target.type!=undefined&&e.target.type.toUpperCase()=="BUTTON"))
        {
            target=e.target;
        }//样式按钮
        else if($(e.target).hasClass('btn')) {
            target=e.target;
            if(e.target.parentElement.tagName=='A')
            {
                //<a><span class="btn">按钮<span></a>
                target=e.target.parentElement;
            }
        }

        if(target!=undefined)
        {
            ///事件执行先后顺序，如果直接在mouseup里面置灰，会屏蔽掉原有的点onclick击事件
            // mousedown>mouseup>onclick>click>on()
            $(target).click(function(){
                //a标签disabled属性无效
                if(target.tagName=='A')
                {
                    $(target).addClass('a-disabled');
                    setTimeout(function(){
                        $(target).removeClass('a-disabled');
                    },2000);
                }
                else{
                    target.setAttribute('disabled','disabled');
                    setTimeout(function(){
                        target.removeAttribute('disabled');
                    },2000);
                }

            });
        }
    };
</script>

<style>
    .a-disabled
    {
        opacity: 0.6;
        cursor: default;
        pointer-events: none;
    }
</style>