FAQ: Functions - Concise Body Arrow Functions

This community-built FAQ covers the "Concise Body Arrow Functions " exercise from the lesson “Functions”.

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This exercise can be found in the following Codecademy content:

Web Development

Introduction To JavaScript

FAQs on the exercise _Concise Body Arrow Functions _

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A post was split to a new topic: I don’t get this lesson

Even more concise code:

const plantNeedsWater = day => day === ‘Wednesday’;

console.log(plantNeedsWater(‘Wednesday’));

2 Likes

And we can write it this consisely, why?

The solution to this exercise confused me a tad…

How are we able to use the concise body function when the correct answer is too long and still results in a multi-line block?

1 Like

When there are multiple lines of code in the block, write it like a regular function expression (with curly braces and a return).

const foo = (baz, bar) => {
    // code
    // code
    // code
    return "some value"
};
1 Like

I struggled with this exercise too.
Whilst concise functions sound useful - I prefer the more readable form of multi-line functions personally.
Still it’s useful to know!

13 Likes

I was good until the last page (review functions):

When I played around with the code I noticed:

const plantNeedsWater = day => day === 'Wednesday' ? 'Water me' : "Don't water me";

can also be on two lines

const plantNeedsWater = day => day === 'Wednesday' 
? 'Water me' : "Don't water me";

… without having to use the ‘return’ statement, or additional code. I was considering this if the true/false answers were a longer statement; to allow for better readability. Is this doable, or should I be considering a better way to keep the code ‘clean’?

I am trying to print the answer:

const plantNeedsWater = day => day === 'Wednesday' ? console.log('water') : console.log('no water');

but nothing happens. Please advise how to do that?

Did you call plantNeedsWater?

1 Like

I dind’t, thanks :slight_smile:

const plantNeedsWater = day => day === 'Wednesday' ? console.log('water') : console.log('no water');
plantNeedsWater('Wednesday'); // returns water
2 Likes

At this point in my learning, I vastly prefer the longhand way of writing functions.

2 Likes

Preference is subjective. Programming is not about subjectivity, but objectivity. By having a preference we end up closing the book on possible ways to simplify a program and better manage memory and resources.

6 Likes

You’re both correct and infuriating. :slight_smile:

6 Likes

Concise arow function seems to work for IF functions.
Example:
userInput2.toLowerCase() === ‘rock’? userInput2+“answer” : “Try again”;
How about when function has 2 more else if parameters ?

Hey @dev0403120509!

Here’s how:

1 == 2 ? 2+2 : 3
-> 3

That’s just a simple if/else conditional. To make it longer, you do this:

1 == 2 ? 2+12 : 2==2 ? 2+21 : 3+5
  ^       ^      ^      ^      ^
 If     do this  if  do this  else
-> 23     
2 Likes

We need to clarify that this is not a function, but a ternary expression.

condition ? value/action if true : default

As Steven has shown above, nested conditions are written into the default slot.

We should also note that if a value is being assigned then we need a variable to receive it.

a = Math.floor(Math.random() * 10 + 1);
b = a < 5 ? -1 : a > 5 ? 1 : 0;
            ---         --- ---   => values
    -----        -----            => conditions
const f = x => x + 5;
const g = x => x - 5;

console.log(a < 5 ? f(a) : a > 5 ? g(a) : a);
                    ----           ----   => action returns value
1 Like

Here’s where it gets interesting…

const f = x => x + 5;
const g = x => x - 5;
const h = x => x;

console.log((a < 5 ? f : a > 5 ? g : h)(a));
                    ___         ___ ___       => reference
                                       ---    => invocation

nested_ternary

console.log(a * b)  // `b` from above

There is some fun to be had running this sequence repeatedly. Haven’t done it, yet, myself, but that is in the offing.

Okay, I’m a bit confused right now. I started this exercise by writing this exact code:

const plantNeedsWater = day => day === 'Wednesday' ? true : false;

But it wasn’t correct apparently since it kept telling me to remove parentheses around the word day.

After reading this whole forum and not finding an answer, I went on and asked codecademy to give me the answer. After clicking the button “give me answer” it gave me this code:

const plantNeedsWater = day => day === 'Wednesday' ? true : false;

Which is the exact same code I’ve wrote before. Is this just a bug in codecademy?

3 Likes

Hi @jessypinkman1234, welcome to the forums!

As long as your code was exactly the same as the solution, yes that would be a bug. I would recommend submitting a bug report with the same info you posted to the forums.