[exercises/concept/fruit-picker] Exercise requires users to be familiar with the throw statement

[nacaru-w]

While I was doing the exercise myself (which is made to test users about the Arrow functions and Callbacks concepts), I came across something that I found a bit confusing: task 3 of this exercise requires users to

[...] throw a new error if err is not null.

This implies using the javascript throw statement as part of the function the exercise asks you to build. However, the Errors concept (where the throwstatement is developed) is to be found much further down the syllabus tree, and the way the instruction is described in the task might make users think that "throwing an error" just means returning a string with an message with an error text as opposed to using the error statement. This is what I did myself, which meant that when running the tests, I got a message from the debugger saying that I was supposed to use something I didn't even know existed to complete the exercise.

I believe this can be easily fixed by either:

• Making sure the instruction of the task is clear about what the user needs to use (the errorstatement). An easy fix to this would be to add a link to its MDN page in the very same paragraph.
• Removing the need to use such statement. This would imply modifying the exercise so that users are required to simply return a string with an error message instead.

[SleeplessByte]

Thanks for bringing this up.

It seems indeed that the prerequisite is missing. We'll have a talk about what's wise here.

[junedev]

Yes, great catch indeed. I will take a closer look what's the best way forward here.

[pikkus]

I know very well how to use arrow functions but I'm really struggling with callback functions, which are poorly explained in the exercise. I'm ok with leaving behind the callback topic until I'm more familiar with it, but why is that blocking my arrow functions as well? This is really annoying...

[junedev]

@pikkus I agree the introduction could probably be improved. I am not sure what would be gained by decoupling callbacks from arrow functions though. You are already free to choose to not do the Callbacks exercise but instead first proceed down the Classes path in the syllabus. But in the end callbacks are needed to understand all of the array utilities (map, forEach, filter, etc.) in the next "layer" of the concept tree and those are also one of the most common use cases for arrow functions and one reason arrow functions were added to the language. That's why I think it makes sense to learn about callbacks and arrow functions in the same exercise.

[sergioreynoso]

Hello, in Task 3 it says "Finish the purchaseInventoryIfAvailable callback function to be used with the grocer's checkInventory API function.", but the checkInventory callback takes a query and a callback. I'm confused as to how I'm to use checkInventory in this exercise.

[obrunopereira]

Hello, in Task 3 it says "Finish the purchaseInventoryIfAvailable callback function to be used with the grocer's checkInventory API function.", but the checkInventory callback takes a query and a callback. I'm confused as to how I'm to use checkInventory in this exercise.

I'm stuck at the same point. Came here for help.

[ievgenk]

Heya @sergioreynoso @obrunopereira ,
I believe what they mean by saying that, is that "purchaseInventoryIfAvailable" is going to be that callback that goes into "checkInventory"

You do not need to use "checkInventroy" in the 3rd task.