How to compare string in expression language

Is there a way to compare to strings in an expression language?
I just want to compare my local ip in the system network tag to specific ip in string format and enable/disable a button in vision based on the result.

The docs should be pretty clear that it’s a simple comparison using =.

<your_ip> = ""

No special function is needed.

In Perspective, the comparison would be done like this (although keep in mind that you might get a machine name instead of the IP):
Screen Shot 2021-03-11 at 10.41.00PM

Thanks for your input But I am using vision 8.0.15
I tried this with an expression tag like this
if ( {[System]Client/Network/IPAddress.Value} = “” ,1,0)
seems like could not compare strings

You can just use {[System]Client/Network/IPAddress} = "" or ! =

Yeah, I tried this too without the if condition but the error is the same as the second attachment above.
with an error message as below
[false, Bad_NotFound, Fri Mar 12 17:04:54 IST 2021 (1615548894049)]

The problem isn’t string comparison. You are trying to use a tag that doesn’t exist in gateway context in an expression tag.

Adding to Phil’s comment, you need to make your expression tag in ‘Vision Client Tags’

Thanks, pturmel and Jordan !
Now able to compare after creating this expression in the client tag.