All language subtitles for 005 Outputting Conditional Content_en

So our filter is now working,

but we can actually select values where we have no data.

And we might wanna show an appropriate message

in such cases,

and that leads us to the second part of this module,

conditional content, which is also important.

Conditional content is about rendering different output

under different conditions.

So I'm not talking about lists,

but about rendering either A or B or C, whatever you need.

And that's something I wanna do here,

in Expenses.js, we render our list of expense items,

but if our filtered expenses, array turns out to be empty,

we render nothing.

Now, we might wanna instead

render a message telling the user that we have no items

for the chosen filter.

And for that, we wanna render content conditionally.

How can we do that?

Well, we can again add a dynamic expression here

in our JSX code and simply use a condition here.

I'm not talking about an if condition

because long statements like this,

the same is true for four loops

are actually not allowed here between these curly braces,

but we can use a ternary expression here.

And we could check if our filtered expenses length

is equal to zero,

which means we have no items

in that filtered expenses array.

And if that's the case, after a question mark,

which is the default JavaScript ternary expression syntax

we render a simple message and a paragraph

where we say, no expenses found.

Otherwise after the colon, we render our list.

So we grab this year, cut it

and removed as empty pair of curly braces now,

and we render this mapping expression in the else case.

And again,

that's the default JavaScript ternary expression syntax,

condition, question mark then what we wanna do

if the condition is met, colon for the else case,

what we wanna do, if it's not met.

And if you save this, you see,

I got no expenses found here for 2022,

but for 2020, I do have my expense.

Of course, that's a bit hard to read,

we can fine-tune this in a second,

but that's how we can render content conditionally.

Of course, long ternary expressions like this

can be a bit hard to read though.

So we can also fine-tune this or restructure this

and reuse this condition,

but then abuse a little trick in JavaScript.

We can add the end operator and then use the content,

the JSX content we wanna render if this condition is met,

JavaScript works such that if you use the end operator,

it basically will return the part after the end operator,

as a result of this overall check here,

if the first condition is met.

So if this first condition is met,

it moves on to the part after the end operator

and it then returns, that value.

And that's what we're abusing here.

And abusing sounds like a bad thing,

this is actually something which is fine to use,

you'll see it in a lot of React projects.

And it simply allows you to write shorter expressions,

because now we can do the same here for our alternative.

There we wanna check if we got more than zero items,

and then we use && to output our list here.

So now I basically split that long ternary expression

into two stand-alone expressions,

which check different conditions,

using this & trick here,

where the part after & is rendered

if the part before & returns true.

And with that, we got the same behavior as before,

as you can tell.

But even that might be too much logic in the JSX code.

So we also got a totally alternative way of handling this.

We can add a variable,

maybe name it, expensesContent, but the name is up to you.

And we assign a default value here.

And the default value could be our message

that no content was found.

And we can store JSX content like this in variables.

We can return it and we can also use it anywhere else,

where we work with values.

So we can store JSX content in the variables,

as I'm doing it here, this is absolutely fine.

You are not limited to using JSX only if you return,

you can also use it to create a value,

which is stored in a variable.

Now, why am I doing that though?

Because now we can edit if check here,

before we return

and we can check if filtered expenses length

is greater than zero,

so if we do have filtered expenses.

And if that's the case,

I wanna overwrite expensesContent.

So I will change the value of this variable

and I will set this then to the result

of this map call here like this.

So this list of expense items,

that's my value stored in expensesContent

if we got a length greater than zero.

And then down there in our returned, JSX code,

we can get rid of all that logic.

And we just add a simple dynamic expression

where we point at expensesContent.

So add this variable.

And this variable holds either this JSX code

or this array of JSX elements.

Both is a renderable and therefore both can be used here.

And now we get a lean JSX snippet which we return,

and we've got our logic in the component function itself.

And we could argue that this is more readable.

And again, if you save that, it works just as before.

And it's up to you, which approach you prefer.

It also depends on the length of the conditions

and the content which is rendered under different cases.

But ultimately this is probably the cleanest way,

but again, it is up to you what you prefer.

I want to show you all options

so that you can go with the way

which you personally lik the most.

I will go with this approach

because I'm a fan of having a lean JSX snippet here.