JSONata - how to test if variable exists

[krambriw]

I have a simple JSONata expression in a Switch node like below. It works as expected when the flow context variable is defined and set to 'on'. But how can I, with JSONata, check if a flow or global context variable really exists and is defined. I have tried null, empty, undefined...

[ghayne]

$exists($globalContext('test'))	

[shrickus]

Gary beat me to it... but I like a slightly different pattern:

Put the JSONata expression into the Property, and then use the output port rules as a kind of "case" statement (good for comparing incoming data to a list of possible string values, for example):

[ghayne]

Brilliant Steve!

[krambriw]

Wonderful!! Thank you both of you, really helpful, my Switch works as I want now!
Best regards, Walter