Below is a sample response from JMeter tool.
<input name="requestId" type="hidden" value="-1859748216"/>
I try the following XPath //input[@name='requestId']
, but it doesn't work, I would like to take only the numeric value -1859748216
You need to get the value attribute using /@value
//input[@name='requestId']/@value
Prefer using newer/improved XPath2 Extractor over XPath Extractor