RegExing a veiwstate

Question

First of all, what is a viewstate? In testautomation I probably need to correlate this value as it is unique for every user logging in?

How can I get the 'value' / token below using regex?

<div>
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="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" />

Answer 1

Read this: RegEx match open tags except XHTML self-contained tags

then if you still want to have a go, use this:

(?<=input )(?:.*)(value\=\".*\")