Javascript 如何使报警提示只显示一次？_Javascript_Html

Javascript 如何使报警提示只显示一次？

javascript html

Javascript 如何使报警提示只显示一次？,javascript,html,Javascript,Html,我只想要一次警报 <head> <script type="text/javascript"> var name; name = window.prompt("Enter name"); </script> </head> 保存一份副本，检查是否存在，然后询问是否存在 function getName() { var n, q = 'Enter name'; if (!window.sessionS

我只想要一次警报

<head>
    <script type="text/javascript">
    var name;
    name = window.prompt("Enter name");
    </script>
</head>

保存一份副本，检查是否存在，然后询问是否存在

function getName() {
    var n, q = 'Enter name';
    if (!window.sessionStorage) {  // if sessionStorage not supported
        return window.prompt(q); // perform other action
    }
    n = window.sessionStorage.getItem('name');
    if (!n) {
        n = window.prompt(q);
        window.sessionStorage.setItem('name', n);
    }
    return n;
}

在提供名称后设置cookie

然后在每次加载页面时检查是否设置了cookie

如果未设置，则显示提示，否则不显示

请使您的代码可测试，并将其发布到JSFIDLE.NET上。是否尝试过？在同一代码块中混合使用大括号和无括号的If语句是我经常遇到的噩梦。@Adam我倾向于只有在有多行时才使用大括号；我也写python，所以我更关注缩进，而不是

{}

sI建议在本例中使用localStorage而不是sessionStorage/我加了牙套，希望你不介意。

<body>
<script type="text/javascript">
 PopupCenter()  //for name to be enter on request form
</script>
</body>

<body>


     <div id="promotion">
     <table border="1">     
            <tr><td><p>
            <script language="JavaScript">
                <!--
                promo = new Array
                promo[1]="PROMOTION!!! save up to 50% if you buy more than $300"
                promo[2]="Open every monday to saturday!!!! from 9 a.m to 10 p.m"
                promo[3]="The 100th customer will win free reel & spool!!"
                promo[4]="Labour sale day 20% off!! Labour sale day 20% off!!"
                promo[5]="Custom parts and reels bearing will be 10% off!!!"
                promo[6]="Come NOW!! HURRY!! while promotion still available!!"
                promo[7]="Shimano from $230, NOWW ONLY $98!!!"

                random_num = (Math.round((Math.random()*6)+1))

                document.write(promo[random_num]);
                -->
                </script>
            </p></td></tr>           
     </table>
     </div>



    </body>

 function PopupCenter(pageURL, title,w,h) {
        var left = (screen.width/2)-(w/2);
        var top = (screen.height/2)-(h/2);
        var targetWin = window.open ("promotion.html", "PROMOTION", 'toolbar=no, location=no, directories=no, status=no, menubar=no, scrollbars=no, resizable=yes, copyhistory=no, width='+580+', height='+485+', top='+100+', left='+400);

        } 
        return sessionStorage.Popupccenter=1;

function getName() {
    var n, q = 'Enter name';
    if (!window.sessionStorage) {  // if sessionStorage not supported
        return window.prompt(q); // perform other action
    }
    n = window.sessionStorage.getItem('name');
    if (!n) {
        n = window.prompt(q);
        window.sessionStorage.setItem('name', n);
    }
    return n;
}