Here is part of the instructions: Write a function nextInLine which takes an array (arr) and a number (item) as arguments. Add the number to the end of the array, then remove the first element of array. The nextInLine function should then return the element that was removed.
yes
I think I might have the first part right. ```
function nextInLine(arr, item) {
// Your code here
arr.push(item);
item.shift();
return item; // Change this line
}
// Test Setup
var testArr = [1,2,3,4,5];
// Display Code
console.log("Before: " + JSON.stringify(testArr));
console.log(nextInLine(testArr, 6)); // Modify this line to test
console.log("After: " + JSON.stringify(testArr));
```
for example
var testArr = [1,2,3,4,5];
console.log(nextInLine(testArr, 6)); // prints 1, what the first element was
console.log(testArr); // testArr is now [2,3,4,5,6]
Hint:
shift is an array method that removes the first element and returns it
ahh okay, they are referring to both. When you pass
testArr to the function nextInLine (such as nextInLine(testArr, 6)), the variable arr inside the function represents the same array as the variable testArr. Inside the function they only want you to change that array that the variable arr represents so that any array can be used as input (when calling nextInLine with testArr as the input, it will change the variable testArr as well).
It is important to think of variables are references to objects, but not the actual object. For example, the array
[1,2,3,4,5] might reside somewhere inside your computer's memory, and the variable testArr simply points to the memory. Reassigning the variable (such as testArr = "something_else") is like pointing to different part of memory, but the actual array might still reside in memory, maybe with another variable pointing to it.var arrayHolderOne = [1,2,3,4];
var arrayHolderTwo = null;
arrayHolderTwo = arrayHolderOne;
// arrayHolderTwo now points to the same array as arrayHolderOne
arrayHolderOne.push(5); // this is adding 5 to the array that arrayHolderOne is pointing to.
console.log(arrayHolderOne); // <-- [1,2,3,4,5]
// even though I didn't directly manipulate the variable arrayHolderTwo,
// the array that arrayHolderTwo points to is the same as a arrayHolderOne
// therefore arrayHolderTwo also equals [1,2,3,4,5]
console.log(arrayHolderTwo); // <- [1,2,3,4,5]
imma look at that code now David.
Ok. I'm still a bit confused. If "arr" and "testArr" are the same thing, or point to the same thing, I would think there would have to be a line like this somewhere in the code:
var arr = [1,2,3,4,5];
var arr = testArr; or var arr = [1,2,3,4,5];But there isn't. Its like they put arr in there, but it's not assigned to anything. They want me to "remove the first element of array", so I would think that code would have to look like this: ```var arr = [1,2,3,4,5];
hold on. i wasn't finished
i don't know how to format this
Hi @Lilyheart and @lantech19446
there were 2 other people stuck on the same lesson, having the same issues.
it's like you're cruising through the lessons at a good pace, then you get to #173 and it's a brick wall.
/*
In Computer Science a queue is an abstract Data Structure where items are kept
in order. New items can be added at the back of the queue and old items are
taken off from the front of the queue.
Write a function nextInLine which takes an array (arr) and a number (item) as
arguments. Add the number to the end of the array, then remove the first element
of array. The nextInLine function should then return the element that was
removed.
*/
/*
To make this easier to understand let's equate it to a real world example of
standing in line at the cash register. The cashier is going to ask for the next
customer in line, and a another customer in the store is going to get in line
for the register.
*/
/*
Now suppose the coffe shop, StarElks, has two registers and two lines for each
register. Each line alreays has some customers in it.
Let's represent those customers in their line with some arrays.
*/
var customersForRegisterA = ["alice", "bob", "carol"];
var customersForRegisterB = ["danny", "eve"];
/*
There are two cashiers who are overly anal retentive, Fred & Ginny.
Both Fred and Ginny are not adapt at social interacting with people.
They also cannot live life happily unless the amount of customers in their
lines remains the same. Therefore, when a new customer enters a line,
Fred or Ginny finishes the transaction of their current customer. If no one
enters their line, they stall their current customer with awkward silence.
Let's say that Fred is operating register A, and Ginny is operating register B.
Both Frad & Ginny currently have a customer.
Let's store those customers as well.
*/
var fredsCustomer = "hailey";
var ginnysCustomer = "isaac";
/*
The manager of StarElks realizes that Fred and Ginny are too afraid to talk to
the customers, so the manage decides to get a javascript program to help manage
the lines for the registers.
Let's call this program (and function), nextInLine.
*/
function nextInLine(lineForRegister, newCustomer) {
// the code here should manipulate the lineForRegister by
// adding the newCustomer and returning who is next
// Hint: do not use the variables customersForRegisterA and customersForRegisterB
var nextCustomer;
// code to manipulate lineForRegister
return nextCustomer;
}
/*
A new customer, Jill, enters the store and gets in line for register A.
Fred realizes this, so he knows he can finish Hailey's transaction.
Fred isn't sure who his next customer is, but he can use the new javascript
program to help.
Prior to this, Fred's customer is Hailey and he has Alice, Bob, and Carol in
line for his register.
*/
var fredsCustomer = nextInLine(customersForRegisterA, "jill");
// Hailey left the store, so Fred's customer is now Alice.
console.log(fredsCustomer); // alice
// Alice is no longer in line, but Jill entered the line.
console.log(customersForRegisterA); // ["bob", "carol", "jill"]
/*
Because the program takes the value that the variables point to, it can be used
for Ginny's line as well.
Another customer, Kevin, enters StarElks. Kevin gets in lien for register B
(Ginny's register).
Prior to this, Ginny's customer is Isaac and she has Danny and Eve in line for
her register.
*/
var ginnysCustomer = nextInLine(customersForRegisterB, "kevin");
// Isaac left the store, so Ginny's customer is now Danny.
console.log(ginnysCustomer); // danny
// Danny is no longer in line, but Kevin entered the line.
console.log(customersForRegisterB); // ["eve", "kevin"]
hopefully that's easier to read now