This content originally appeared on DEV Community and was authored by Coding Bugs
In my experience, more than 15 years of coding, programming, architecting, I've found people implementing code with no rules or standards and, sometimes, people believing they follow some rules but, in reality, they are not applying by themselves. I was in that situation a lot of times and keep being sometimes as well. I've written this article to show what I think is a good practice and makes us being good professionals.
The issue
The following React code renders a list of items in case of the array passed has them.
function List(props) {
const items = props.items;
return <ul>
{items && items.map(i => <li key={i}>{i}</li>)}
</ul>;
}
function App() {
const collection = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0];
return <List items={collection} />;
}
ReactDOM.render(App(), document.getElementById('app'));
Do you think there is something wrong with the code? This code works perfectly fine, it creates a li node with the number as the value.
What happens if the array has no items in it? The ul node will be rendered as well but there won't be any li node and no items in there. This is not a big issue but something not completely well.
We can modify the code in this way:
function List(props) {
const items = props.items;
// *** notice how the code is modified and complex increases
return items &&
<ul>
{ items.map(i => <li key={i}>{i}</li>) }
</ul>;
}
function App() {
const collection = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0];
return <List items={collection} />;
}
ReactDOM.render(App(), document.getElementById('app'));
Like the previous case, this code is working fine, it does what it is supposed to do.
So, let me ask the same question as before, what happens if the array has no items in it?
In this case, a false value and no HTML node are returned. The issue here is that we return different kinds of items depending on the items property passed.
Why is this an issue? In fact, this is just a concept issue more than a coding issue. Returning the same kind of item in this function will make it easier for testing, make it easier to maintain, make it easier to read because it will be consistent and other methods calling this one will receive exactly what they expect and won't have the necessity to check if retrieves a boolean or a component.
The next code modification must have in mind this premise so it'll be like the following:
function List(props) {
const items = props.items;
// check if items is not empty
const isEmpty = !(items && items.length > 0);
// always return a React component
return isEmpty
? <React.Fragment />
: (<ul>
{ items.map(i => <li key={i}>{i}</li>) }
</ul>);
}
function App() {
const collection = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0];
return <List items={collection} />;
}
ReactDOM.render(App(), document.getElementById('app'));
It seems that our code makes more sense now, doesn't it? We always return a component for any of the options or paths our code takes. If items is not empty, a ul node is returned plus a li node per item inside, a React component in fact.
If there is no items, a React.Fragment component is returned. Both of them are React components, no need for callers to check it.
As a professional programmers that we are, we must give meaning and name our objects.
You may noticed we have few objects here in our code, an empty list component, an item list component, an item component and a manager component. Each of them with a unique responsibility (following the Single Responsibility principle that I'll talk in a future article) and a simple code easy to understand, to maintain and to test.
function ListItem(props) {
return <li>{props.value}</li>;
}
function ItemList(props) {
const items = props.items;
return <ul>
{ items.map(i => <ListItem key={i} value={i} />) }
</ul>;
}
function EmptyList() {
return <div>No items in the list</div>; // or <React.Fragment />
}
function ListManager(props) {
const items = props.items;
const isEmpty = items && items.length <= 0;
return isEmpty
? <EmptyList />
: <ItemList items={items} />;
}
function App() {
const collection = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]
return <ListManager items={collection} />;
}
ReactDOM.render(App(), document.getElementById('app'));
I think this code looks like much better than the first one. Reviewers'll see the person behind the code thought how to face the problem, the constraints, and the paths to take around of it.
Wrapping up
As I wrote some paragraphs above, professional programmers must give meaning to the code. Coding can be done by anyone, programming in a good way with sense are just a subject of professionals.
What do you think about the exercise made in this article?
Hope this can be useful to you or just have fun reading it.
This content originally appeared on DEV Community and was authored by Coding Bugs
Coding Bugs | Sciencx (2021-04-24T16:16:08+00:00) Professionals never return React.Fragment. Coders do.. Retrieved from https://www.scien.cx/2021/04/24/professionals-never-return-react-fragment-coders-do/
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