I'm very new to Javascript: I've been working with it for a few weeks casually now. This is my first post, so I apologize if I'm not thorough enough, but I think I have been below!
I want to create a function VendingMachine(snack, cash) that has a list of 4 items and their prices that takes 2 arguments, "snack name" (snack) and "cash inserted" (cash). I've tried making the list an object and an array and only have semi-success with the array, but I believe the object is truly the path I want to take because...
When using an array with nested arrays for the snacks list, the only problem is that if the for() loop doesn't find the "snack" value in any of the arrays, it prints 'undefined' instead of "Sorry, try again."
With the list of items in the machine in an object, I want to check that "snack ==== object.KEY" and that "cash >= VALUE" of that KEY. My problem here is that I don't know the syntax concerning objects well, and the explanations and answers I see other people posting are too abstract for me to prehend at the moment, or are more plex loops/problems and don't really seem to be applicable to my situation. All things except this (which I couldn't figure out either/didn't work):
for(var key in objects) {
var value = objects[key];
}
// Using an array
function vendingMachine(snack, cash) {
//declare nested arrays of snacks & costs
var snacks = [
["Espresso", 1],
["Cappuccino", 2.50],
["Chocolate bar", 2],
["Potato Chips", 3.50]
]
//iterate through array to match snack and check funds
for (var i = 0; i < snacks.length; i++) {
if (snack === snacks[i][0] && cash >= snacks[i][1]) {
if (snack === "Potato Chips") {
console.log("Your " + snack + " have been served");
} else {
console.log("Your " + snack + " has been served");
}
}
else if (snack === snacks[i][0] && cash <= snacks[i][1]) {
console.log("Insufficient funds. Please insert more cash.");
}
}
}
// Using an object (inplete or perhaps just VERY incorrect, I'm aware, hence why I'm here to understand why!)
function vendingMachine(snack, cash) {
//declare nested arrays of snacks & costs
var snacks = {
"Espresso": 1,
"Cappuccino": 2.50,
"Chocolate bar": 2,
"Potato Chips": 3.50
}
if (snack === snacks.hasOwnProperty() && cash >= snacks.key) {
if (snack === "Potato Chips") {
console.log("Your " + snack + " have been served");
} else {
console.log("Your " + snack + " has been served");
}
}
else if (snack === snacks.hasOwnProperty() && cash <= snacks.key) {
console.log("Insufficient funds. Please insert more cash.");
}
else if (snack != snacks.hasOwnProperty()) {
console.log(snack + " does not exist. Please try again.") //returns undefined
}
}
I'm very new to Javascript: I've been working with it for a few weeks casually now. This is my first post, so I apologize if I'm not thorough enough, but I think I have been below!
I want to create a function VendingMachine(snack, cash) that has a list of 4 items and their prices that takes 2 arguments, "snack name" (snack) and "cash inserted" (cash). I've tried making the list an object and an array and only have semi-success with the array, but I believe the object is truly the path I want to take because...
When using an array with nested arrays for the snacks list, the only problem is that if the for() loop doesn't find the "snack" value in any of the arrays, it prints 'undefined' instead of "Sorry, try again."
With the list of items in the machine in an object, I want to check that "snack ==== object.KEY" and that "cash >= VALUE" of that KEY. My problem here is that I don't know the syntax concerning objects well, and the explanations and answers I see other people posting are too abstract for me to prehend at the moment, or are more plex loops/problems and don't really seem to be applicable to my situation. All things except this (which I couldn't figure out either/didn't work):
for(var key in objects) {
var value = objects[key];
}
// Using an array
function vendingMachine(snack, cash) {
//declare nested arrays of snacks & costs
var snacks = [
["Espresso", 1],
["Cappuccino", 2.50],
["Chocolate bar", 2],
["Potato Chips", 3.50]
]
//iterate through array to match snack and check funds
for (var i = 0; i < snacks.length; i++) {
if (snack === snacks[i][0] && cash >= snacks[i][1]) {
if (snack === "Potato Chips") {
console.log("Your " + snack + " have been served");
} else {
console.log("Your " + snack + " has been served");
}
}
else if (snack === snacks[i][0] && cash <= snacks[i][1]) {
console.log("Insufficient funds. Please insert more cash.");
}
}
}
// Using an object (inplete or perhaps just VERY incorrect, I'm aware, hence why I'm here to understand why!)
function vendingMachine(snack, cash) {
//declare nested arrays of snacks & costs
var snacks = {
"Espresso": 1,
"Cappuccino": 2.50,
"Chocolate bar": 2,
"Potato Chips": 3.50
}
if (snack === snacks.hasOwnProperty() && cash >= snacks.key) {
if (snack === "Potato Chips") {
console.log("Your " + snack + " have been served");
} else {
console.log("Your " + snack + " has been served");
}
}
else if (snack === snacks.hasOwnProperty() && cash <= snacks.key) {
console.log("Insufficient funds. Please insert more cash.");
}
else if (snack != snacks.hasOwnProperty()) {
console.log(snack + " does not exist. Please try again.") //returns undefined
}
}
4 Answers
Reset to default 3Using some modern javascript I have updated your vending machine and also made it return change.
function vendingMachine(snack, cash) {
const snacks = [
{ name: 'Espresso', price: 1 },
{ name: 'Cappuccino', price: 2.50 },
{ name: 'Chocolate', price: 2 },
{ name: 'Potato', price: 3.50 }
];
const selected_snack = snacks.find(item => item.name === snack);
if (selected_snack) {
if (selected_snack.price === cash) {
return `Your ${snack} have been served`;
}
else {
if (selected_snack.price > cash) {
return `Insufficient funds. Please insert more cash.`;
}
else {
return `Your ${snack} have been served. Here is your $${cash - selected_snack.price} change.`;
}
}
}
else {
return `${snack} does not exist. Please try again`
}
};
console.log(vendingMachine('Espresso', 12));
First of we convert the snacks into an array of objects, each one of them having a name and a price keys.
Next we use the Array.find() method to search the list of snacks for the snack in question by it's name. The function will return a single object, if you want multiple results that match some criterion use Array.filter() instead.
So if we have a match we can say if (selected_snack) which evaluates to true, otherwise if there is not match then selected_snack would be undefined so basically a less verbose way to say if (selected_snack !== undefined).
The rest of the function is almost self-explanatory, the only changes I made is that I'm not console logging inside of the function, instead I am using a return statement.
Also in case you wonder what those weird looking ${} things are, check out about Template Literals, extremely easy and convenient to use so you don't have to write ugly code such as "Your " + snack + " have been served".
I hope that helps, if you have any questions let me know.
I would probably create the list as array of objects as it give you flexibility when you need to add more details about snacks. So the list could be like
const snacks = [
{
"name": "Chips",
"price": 123
},
{
"name": "Drinks",
"price": 456
}
];
Now your vendingMachine function can be very simple which will find the matching snack and price. Something like this
function vendingMachine(name, price) {
const canSnackBeServed = snacks.find(snack => snack.name === name && price >= snack.price);
if (canSnackBeServed) {
console.log("Your " + name + " has been served");
} else {
console.log("Snack doesn't exist or Insufficient funds.");
}
}
Hope this helps
It's a little difficult to see exactly what is wrong with the code you have; I'd suggest one of the main problems might be how you're using snacks.hasOwnProperty().
Object.hasOwnProperty takes an argument which is a key, and it returns a boolean. So in your example, the code should probably look more like snacks.hasOwnProperty(snack), which would check whether the snacks object has the property snack.
How you store the data is up to you, and you're fairly close to being able to get it to work. One thing to note is that snacks.key will attempt to get the key property of snacks, which is probably not what you wanted to do here. Instead, something like snacks[snack] might have been more appropriate. You can use either dot notation or square bracket notation to get properties of objects.
With all that being said, here's some code which might illustrate a few new concepts, hopefully without being too abstract. Don't worry too much about arrow functions; they're basically the same as regular functions, just with a different syntax.
What I've setup below would allow you to have a generic function getSnack, which will determine which function it should use to get the correct snack data. This means that you don't have to worry about which way you've stored the snack data at the point of use.
From then on, the code is really quite similar to what you have; the other concept we have here is array destructuring, which is a fun one to learn, and can save a little on syntax.
Hopefully this helps, please ask away with any questions.
const snacks = {
"Espresso": 1,
"Cappuccino": 2.50,
"Chocolate bar": 2,
"Potato Chips": 3.50
};
const snacksArray = [
["Espresso", 1],
["Cappuccino", 2.50],
["Chocolate bar", 2],
["Potato Chips", 3.50]
];
const getSnackFromArray = (array, itemName) => array
.find(x => x[0] === itemName)
const getSnackFromObject = (snackDataObject, itemName) => (
snackDataObject.hasOwnProperty(itemName)
? [itemName, snackDataObject[itemName]]
: undefined
)
const getSnack = (data, itemName) => Array.isArray(data)
? getSnackFromArray(data, itemName)
: getSnackFromObject(data, itemName)
const vendingMachine = (snack, cash) => {
const snackData = getSnackFromObject(snacks, snack);
if (snackData === undefined) {
console.log(snack + " does not exist. Please try again.")
return;
}
const [snackName, cost] = snackData;
if (cash >= cost) {
console.log("Your " + snack + " have been served")
} else {
console.log("Insufficient funds. Please insert more cash.")
}
}
vendingMachine('Espresso', 1.1)
vendingMachine('Espresso', 1)
vendingMachine('Espresso', 0.9)
vendingMachine('Expresso', 0.9) function vendingMachine(snack, cash) {
//declare nested arrays of snacks & costs
var snacks = {
"Espresso": 1,
"Cappuccino": 2.50,
"Chocolate bar": 2,
"Potato Chips": 3.50
}
if (snacks.hasOwnProperty(snack) && cash >= snacks[snack]) {
if (snack === "Potato Chips") {
console.log("Your " + snack + " have been served");
} else {
console.log("Your " + snack + " has been served");
}
}
else if (snacks.hasOwnProperty(snack) && cash <= snacks[snack]) {
console.log("Insufficient funds. Please insert more cash.");
}
else if (snack != snacks.hasOwnProperty(snack)) {
console.log(snack + " does not exist. Please try again.") //returns undefined
}
}