JMeter "if controller" with parameters?

Question

I was reading the JMeter documentation and came across this info box about "If Controllers":

No variables are made available to the script when the condition is interpreted as Javascript. If you need access to such variables, then select "Interpret Condition as Variable Expression?" and use a __javaScript() function call. You can then use the objects "vars", "log", "ctx" etc. in the script.

I don't quite follow this. Does this mean if I want access to a "User Defined Parameter" then I can access it only by writing some JavaScript? The example that follows this box then refers to "${COUNT}"

Could someone clarify the usage of the If Controller, maybe with an example or two?

Answer 1

All these answers are wrong! You need to put the variable reference in quotes, like so:

"${my_variable}"=="foo" 

Answer 2

You can simply use something like

${my_variable}=='1' 

Sometimes JMeter documentation can be confusing :)

Edit 27 september 2017:

The answer here works but has a very bad performance impact when number of threads exceeds 40.

See below for correct and most performing answer:

• https://stackoverflow.com/a/46976447/460802

See:

• https://bz.apache.org/bugzilla/show_bug.cgi?id=61675