有时会引发Null参考异常 [英] Null Reference Exception is thrown sometimes

问题描述

<script language="javascript">
    res = "&res="+screen.width+"x"+screen.height+"&d="+screen.colorDepth
        top.location.href="Login.aspx?action=set"+res
    </script>

源错误:

Source Error:

An unhandled exception was generated during the execution of the current web request,Information regarding origin and location exception can be identified using the exception stact trace below.

Stack trace:

[Null ReferenceException: object reference not set to an instance of an object.]
page_Load(object sender EventArgs e)+143
and next from System.Web

在Page_Load事件IAM的aspx.cs页面中检查

In aspx.cs page in Page_Load event iam checking for

if (Request.QueryString["action"] != null)
{
 Session["ScreenResolution"] = Request.QueryString["res"].ToString();
}

然后也会出现Null ReferenceException异常.

Then also Null ReferenceException exception arises.

推荐答案

将调整大小的代码置于超时范围内:

place the resize code in a timeout:

setTimeout(function() {
    res = "&res="+screen.width+"x"+screen.height+"&d="+screen.colorDepth
    top.location.href="Login.aspx?action=set"+res
}, 0);

这是必需的，因为脚本代码不能确定地执行.有时，它会在计算和填充屏幕尺寸之前运行.

在以下位置检查相同的情况:
http://stackoverflow.com/questions/7976369/null-reference-exception-is-有时会抛出 [ ^ ]

This is required because script code does not execute deterministically. Sometimes it will run before the screen dimensions have been calculated and populated.

check for the same scenario at:
http://stackoverflow.com/questions/7976369/null-reference-exception-is-thrown-sometimes[^]

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