请问如何利用javascript检查文件是否存在？

7ero 2003-08-01 11:28:09

请问如何用javascript检查一个图象文件是否存在，如果存在显示这个图象，不存在择显示默认图象

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awaysrain 2003-08-01

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转贴江南昆虫的代码
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<html>
<head>
<title>利用XMLHTTP检测网址及探测服务器类型</title>
<META http-equiv=Content-Type content="text/html; charset=gb2312">
<meta name="Generator" content="EditPlus">
<meta name="Author" content="JnKc">
<meta name="Keywords" content="">
</head>
<body>
<input type="text" id="jnkcInput" value="http://www.csdn.net" size="50"><button id="chk">检测</button>
<div id="jnkc_show"></div>
<SCRIPT LANGUAGE="VBScript">
Dim i,jnkcUrl,jnkcHTML,jnkcStatus,jnkcServer
Function chk_onClick()
jnkcUrl = jnkcInput.value
Call GetDetail
i = i+1
jnkc_show.innerHTML = "<hr><pre><font color=red>" & i & "、" & jnkcUrl & "</font><br/>" & jnkcStatus & "</pre>" & jnkc_show.innerHTML
End Function
Dim jnkcXMLHTTP
Sub GetDetail
Set jnkcXMLHTTP = CreateObject("Microsoft.XMLHTTP")
jnkcXMLHTTP.OnReadyStateChange = GetRef("GetStatus")
jnkcXMLHTTP.Open "GET", jnkcUrl, False
On Error Resume Next
jnkcXMLHTTP.Send
Set jnkcXMLHTTP = Nothing
End Sub
Sub GetStatus
If jnkcXMLHTTP.ReadyState <> 4 Then
Exit Sub
End If
If jnkcXMLHTTP.Status = 404 Then
jnkcStatus = "该网页不存在！"
ElseIf jnkcXMLHTTP.Status < 200 Then
jnkcStatus = "客户端错误，信息：" & CStr(jnkcXMLHTTP.Status) & " " & jnkcXMLHTTP.StatusText
ElseIf jnkcXMLHTTP.Status < 300 Then
jnkcStatus = "成功，该网页能访问。"
ElseIf jnkcXMLHTTP.Status < 400 Then
jnkcStatus = "重定向，信息：" & CStr(jnkcXMLHTTP.Status) & " " & jnkcXMLHTTP.StatusText
ElseIf jnkcXMLHTTP.Status < 500 Then
jnkcStatus = "客户端错误，信息：" & CStr(jnkcXMLHTTP.Status) & " " & jnkcXMLHTTP.StatusText
ElseIf jnkcXMLHTTP.Status < 600 Then
jnkcStatus = "服务器错误，信息：" & CStr(jnkcXMLHTTP.Status) & " " & jnkcXMLHTTP.StatusText
Else
jnkcStatus = "域名不可用或网络连接错误，信息：" & CStr(jnkcXMLHTTP.Status) & " " & jnkcXMLHTTP.StatusText
End If
If jnkcXMLHTTP.Status < 600 Then Call GetServer
End Sub
Sub GetServer
jnkcServer = jnkcXMLHTTP.GetResponseHeader("Server")
If jnkcServer <> "" Then
jnkcStatus = jnkcStatus & "<br/>HTTP服务器：" & jnkcServer
End If
jnkcStatus = "<b>" & jnkcStatus & "</b><br/>所有反馈信息：<br/>"& jnkcXMLHTTP.GetAllResponseHeaders
End Sub
</SCRIPT>
</body>
</html>