AppleScript:IF command doesn't execute - if-statement

Question

I am a beginner at AppleScript so I really don't know a lot. I have been trying to make the user select from a list of situations and then based on what they choose have an appropriate response. However, I have run into a few problems:
The script runs but doesn't display the notification.
Is there a better way than just chaining a lot of IF statements?
PS: I am nowhere near finishing this whole script.
on run
choose from list {"Thunderstorm", "Flood", "Heatwave", "Hazmat"} with prompt "Please select one of the emergency situations below" without multiple selections allowed and empty selection allowed
return the result as string
if string is Thunderstorm then display notification "hello"
end run

Answer 1

You made some pretty good guesses about what the sample code you were looking at does; but some of those guesses were wrong. With time you’ll get a better feel for how AppleScript works.
You have the situation names entered correctly as strings in the choose from list line, by surrounding their text with quotes. But in the check to see whether it’s a thunderstorm, you do not surround that text with quotes. AppleScript is looking in a variable called Thunderstorm for its contents, not looking at the string of text “Thunderstorm”.
return the result as string does not create a variable called string but rather ends the handler called run, returning the result to whatever code called run, as a string of text. To assign the result of choose from list to a variable, use something like set theSituation to the result as string.
Here’s an example of how your code might work better:
on run
--get the situation we're dealing with
choose from list {"Thunderstorm", "Flood", "Heatwave", "Hazmat"} with prompt "Please select one of the emergency situations below" without multiple selections allowed and empty selection allowed
copy the result as string to theSituation
--Thunderstorms require that the user be immediately notified
if theSituation is "Thunderstorm" then display notification "hello"
end run
Since you have this as a run handler, you probably don’t want to return any result, as you rarely call run handlers. But if you do need to return the result, the last line of the handler (just before end run) would be:
return theSituation
You might look around for an AppleScript tutorial that fits your needs. Apple has their Introduction to AppleScript Language Guide.
IF statements can be chained using if/else if/else if:
on run
--get the situation we're dealing with
choose from list {"Thunderstorm", "Flood", "Heatwave", "Hazmat"} with prompt "Please select one of the emergency situations below" without multiple selections allowed and empty selection allowed
copy the result as string to theSituation
--Thunderstorms require that the user be immediately notified
if theSituation is "Thunderstorm" then
display notification "hello"
else if theSituation is "Flood" then
display notification "hike pants"
else if theSituation is "Heatwave" then
display notification "Play Bing Crosby"
else if theSituation is "Hazmat" then
display notification "Use highway 183"
end if
end run
There is no switch/case control structure in AppleScript.