长按识别二维码

长按原生js写法

<script>
    var num = 0 ;
    function whichElement(e){
        var timer_alert = setTimeout(function() {
            if(e.which==1) {
                num++
                if(num==2){
                    num=0;
                    alert( "鼠标长按" );
                }else{
                    whichElement( e );
                }
            }
        }, 1000) ;
    }
</script>