Question

Please tell me which code or process turns a gridview links into a format like

javascript:__doPostBack(‘ctl00$…

Answer 1

Asp.Net uses the __doPostback javascript function called _doPostBack(). The function is –

function __doPostBack(eventTarget, eventArgument) {
 if (!theForm.onsubmit || (theForm.onsubmit() != false)) {
  theForm.__EVENTTARGET.value = eventTarget;
  theForm.__EVENTARGUMENT.value = eventArgument;
  theForm.submit();
 }

This function is used to submit the form back to the server. _doPostBack accepts arguments – event target and event arguments by using hidden variables __EVENTTARGET and __EVENTARGUMENT. This tells the server which control caused the postback and also passes appropriate arguments to the server.

if you have this code in your aspx page –

<asp:LinkButton ID="lnkButton" runat="server">LinkButton</asp:LinkButton>

The corresponding generated markup will be –

<a id="LinkButton1" href="javascript:__doPostBack('lnkButton','')">LinkButton</a>

So, say you click on a link button, the page is postback by the __doPostBack() function. Then, the page is recreated at server with the respective control state on the page. To get the state of each control on the page mechanisms like viewstate are used. Once the page is loaded, the server computes and renders the response markup.