How to check if a callback function parameter is a specific string?

Question

JavaScript

There is a function with three callback functions

function offerMeal(
  clientPreferences,
  offerVegan,
  offerMeat,
) {

If clientPreferences returns the string 'vegan', return the call to offerVegan, otherwise return the call to offerMeat.

I'm writing through if/else, and I can't figure out how to specify a condition that if 'vegan' gets into the parameter, offerVegan should be called.

Here's what's worked out so far:

if (clientPreferences=== 'vegan') {
    offerVegan();
  } else {
    offerMeat();
    }

Thanks in advance!

Answer 1

In order to get the return value from a function, that function must be called, which you forgot to do.
Corrected code:

const preferences = clientPreferences();
if (preferences === 'vegan') {
  offerVegan();
} else {
  offerMeat();
}

Answer 2

Where is the guarantee that clientPreferences contains a string, and not some object or function? There are no such guarantees, so it makes sense to first check the type of a variable with typeof, and only if it is a string to check for a match with the word vegan.