在 Javascript 中读取服务器端变量

Question

I am using embeded flash for displaying the camera video inside an asp.net project for passing the camera inf. I am writing variables from flash to the server using Tamper Data extension I know it is sending ok.

The problem is reading it with javascript. How can I? I'm trying to use JSP with the <%...%> but I am not able to read it properly.

This is the code I am using:

document.getElementById("txtID").value = "<%=varActionServer.Value%>";

Where txtID is a textbox and varActionServer.Value is the value of the Server variable that I want.

Answer 1

You need to understand the big gap between client-side and server-side. Serverside variables can only tell you what the server knew when it built the page and before it sent it to the client. JSP is a serverside technology and it, too, can only know what the server knew before it sent the page.

What you are trying to achieve is client-side; that after the page has gone to the client, the page can still be updated. For this, you must forget JSP.

I assume that you are going via the server because you already have a working solution that gets data from the camera, through flash, to the server. In that case you can read data from the server using ajax. The simplest route is jQuery.ajax

Another option might be to throw out the flash solution and use something else. Here' an SO question about that approach: Access camera from a browser