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JavaScript JavaScript Loops, Arrays and Objects Tracking Multiple Items with Arrays Removing Items From Arrays

Posted by Margaret James
Margaret James
9,444 Points

Retrieving removed variable for New Array

var orderQueue = ['1XT567437','1U7857317','1I9222528'];
var shipping = [];

var firstItem = orderQueue.shift();

shipping.push(firstItem);

I'm in the Code Challenge and not sure why the 'firstItem' variable I created isn't functioning when I try to use it to add to my new 'shipping' array . What am I missing?

My error is "It doesn't look like you stored the first item from the array in the shipping variable."

Am I able to use the array storing property as the value of a new variable? Or am I just executing it incorrectly?

Margaret James
Margaret James
9,444 Points 
var orderQueue = ['1XT567437','1U7857317','1I9222528'];

var shipping = [orderQueue.shift()]

Also - technically I don't understand why this alternate solution isn't working either.

P.S. I know the simple way of doing this, just curious about the transitive properties of array variables.

1 Answer

Marcus Parsons
Marcus Parsons
15,719 Points
Marcus Parsons
Marcus Parsons
15,719 Points

Hi Margaret,

Your first code is technically correct and works as expected. But for challenges, you should only do what you're asked to do. You're only asked to create one variable, not two, so that's why the challenge won't let you pass.

Also, in your 2nd set of code, even though this works, too, it's unnecessary to include the brackets because the shift method returns an array (in circumstances such as this) so you don't need to explicitly define it as an array by using brackets.

This is the simplest solution:

var orderQueue = ['1XT567437','1U7857317','1I9222528'];
var shipping = orderQueue.shift();
Iain Simmons
Iain Simmons
Treehouse Moderator 32,305 Points

Actually Marcus Parsons, shift returns the value of the removed element, not an array containing the value, so you would need to include the square brackets, or declare the variable as an empty array and then push to it.

Alternatively, you could use the splice Array method, which does return an array of any removed elements (and can also be used to simultaneously add elements to the array):

var orderQueue = ['1XT567437','1U7857317','1I9222528'];
var shipping = orderQueue.splice(0, 1); // start at index 0, remove 1 item