I'm learning how to return functions from other functions in JavaScript. Here is my code that works:
var passengers = [
{ name: "Jane", ticket: "coach" },
{ name: "Evel", ticket: "firstclass" },
{ name: "John", ticket: "coach" },
{ name: "Bob", ticket: "premium"}
];
function createDrinkOrder(passenger) {
var orderFunction;
if (passenger.ticket === 'firstclass') {
orderFunction = function() {
console.log(passenger.name + ', would you like wine or cocktail?');
};
} else if (passenger.ticket === 'premium') {
orderFunction = function() {
console.log(passenger.name + ', would you like some wine?');
};
} else {
orderFunction = function() {
console.log(passenger.name + ', soda or water?');
};
}
return orderFunction;
}
function serveOnePassenger(passenger) {
var getDrinkOrderFunction = createDrinkOrder(passenger);
getDrinkOrderFunction();
// createDrinkOrder(passenger);
}
// General function to serve passengers:
function servePassengers(passengers) {
for (var i = 0; i < passengers.length; i++) {
serveOnePassenger(passengers[i]);
}
}
servePassengers(passengers);
My question is about 'serverOnePassenger' function: when I comment out the first 2 lines in this function and uncomment the 3rd line instead, nothing happens in the console anymore. Why do I have to declare a variable and then assign a function to it, and only then call this var in order for this code to work? Thanks!
Your own question title is basically the answer: you've written the createDrinkOrder()
function as something that returns another function. If you make a function but never call it, the function won't do anything.
You don't need a variable involved as in your serveOnePassenger()
function. You could create the function and call it with one statement:
createDrinkOrder(passenger)();
That calls createDrinkOrder()
and then immediately uses the returned value as a function.
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