In this article we are going to see function helper of jmeter. As we know, we use jmeter function to get various information for using as data while testing and we use this format {$__functionName(parameter1, parameter 2, ...)} to use them

So, what is Function Helper? It's simple an UI that helps to understand the functions and provide the variable string directly usable in the jmeter scripts. To start Function Helper, we need to
open jmeter  > Click Options > click Function Helper Dialog.

And we will get this UI.

The working is simple,
Step1: Select a function from drop down
Step2: Insert value according the description of the paramter
Step 3: Click Generate and we will get formatted string used in jmeter script.
If we need multiple variables, we can add or delete( depends on which function we use)