jcjmcclean/react-simple-hooks-example

Example of using the state hook with react

Simple hooks example

Overview

Following this example, you can see how to handle API requests for data which is used in a single place. We cover sharing data from parent (ColoursPage) to child (ColoursListComponent) component through input props and requesting data from an external function.

Sample code

Code for this example can be found here:

• Simple hooks code sandbox
• Git repo

Files

This example contains a page component (which is included in the main app component), a context and a list component.

colours.context.ts ColoursContext

This provides context (data/state/functions) to components (or pages) within the colours module.

Here is a quick breakdown of this file:

Creating the ColoursContext function and returning an object.

function ColoursContext() {
  return {
    ...
  };
}

Creating the getColours method, which calls an API endpoint and returns a parsed response.

getColours: () => {
  return axios.get("https://reqres.in/api/colours").then(res => {
    return res.data.data;
  });
}

colours.page.tsx ColoursPage

This is the outer template, which is included in the main app component.

Here is a quick breakdown of this file:

Creating the ColoursPage function component.

function ColoursPage() {
  ...
}

Calling ColoursContext, so we can call it's inner functions later.

 const coloursContext = ColoursContext();

Using React hooks to create a colours state on the page.

 const [colours, setColours] = React.useState([]);

Code inside React.useEffect runs first when the component has mounted. The empty array after the function closes tells React to only run this once. You can use this array to specify values for React to watch, then when these values change, it will re-run the code in useEffect. See the React docs for more.

 React.useEffect(() => {
 }, []);

We call getColours from our instance of ColoursContext and wait for the response. We then update our colours hook, using setColours to the response value.

 coloursContext.getColours().then(response => {
   setColours(response);
 });

Finally we render the component. We set a colours prop value on ColoursListComponent to the value of colours in our ColoursPage state.

 // Render coloursPage component
 return (
   <div>
     <h1>Colours page</h1>
     <ColoursListComponent colours={colours} />
   </div>
 );

colours.list.component.tsx ColoursListComponent

Creating the ColoursListComponent function component, defining that it accepts input props and returning JSX to be rendered.

function ColoursListComponent(props: any) {
  return (
    <ul>
      ...
    </ul>
  );
}

Looping through the colours array and output each colour as a list item.

{props.colours.map(function(colour, index) {
  return (
    <li key={index}>
      {colour.name} {colour.color}
    </li>
  );
})}