Tuesday, May 24, 2005
Calling a server side func in JavaScript with document.createElement('script')
CAUTION: THIS DOESN'T SEEM TO WORK ALL THE TIME. I'VE GONE BACK TO THE HIDDEN IFRAME TECHNIQUE
The following bit of JavaScript and C# code work to gether to do
some remote scripting from the browser to the server. Basically
some javascript function running on the client wants to call the
'ServerFunc' C# code, and pass it a single parameter named "user".
See:
- http://www.htmlcodetutorial.com/help/archive.php/o_t__t_1288__ie6-can-t-load-dynamic-and-ltscript-and-gt-element-s-src-url.html
- http://dojo.jot.com/RemoteScriptingRevisited
// Within a javascript function that wants to call the server:
ServerCall("ServerFunc&user="+User);
// The ServerCall function calls a function in the MYPAGE.aspx on the server.
function ServerCall(call){
var head = document.getElementsByTagName("head")[0];
var script = document.createElement('script');
script.src = "MYPAGE.aspx?nocache="+new Date().getTime()+"&cmd="+call;
//alert(script.src);
script.type = 'text/javascript';
head.appendChild(script);
}
NOTE: The rest is C# code in the aspx. If you're not into C#, replace this with whatever you like. The ServerCall() bits should still work.
// Within MYPAGE.aspx’s Page_Load(), we find the desired function and call it.
// Long live reflection
private void Page_Load(object sender, System.EventArgs e){
// Find and execute the command
MethodInfo m = GetType().GetMethod("page"+Request["cmd"]);
if (m==null)
m = GetType().GetMethod("pageDefault");
m.Invoke(this,null);
}
// the m.Invoke() in Page_Load() calls this function. Note, we prepend each page
// function with the word 'page' -- this way baddies can't run arbitrary funcs
public void pageServerFunc(){
string user = Request["user"]; // This came from the client
Script.Append("alert('You can do anything in here');");
Script.Append("SomeClientFunc('Then call a client func to wrap up!');");
Response.Write(script.ToString());
Response.Flush();
Response.Close();
}
StringBuilder script = new StringBuilder();
