how does the hidden field keep its value on post back

Does any body have any idea how does the hidden field keep its value on post back when it is value is set from javascript and not from the server side code?

Can I create a tex开发者_运维百科t box that has this feature?

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I worry I'm not understanding your question... but <input type="hidden" /> name/values get passed with a form like any other input, and you can certainly set their values with JavaScript, if you want. when you submit the form, it doesn't care - or even know - how the input fields got their values.