__doPostBack method

I want to know why we use __doPostBack methods. Is it a buil开发者_如何学Pythond-in JavaScript method or a user defined function and what does this code do?

onclick="javascript:setTimeout('__doPostBack(\'SectionA$1\',\'\')', 0)

I am getting an error for this method:

object expected

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doPostBack is a javascript function that asp.net uses to submit the main form for executing the server-side code of your application.

Buttons are postbacks after clicking on them, however some other controls does not postback. So they calls the doPostBack javascript for simulate the postback action.

In your case, you might having trouble with your server-side control. This usually happens while having some problem about configuring the controls that uses the mechanism above. So you are interested with the wrong side now I suppose.

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It's __doPostBack with two _ characters.