React + Fetch - HTTP POST Request Examples
Below is a quick set of examples to show how to send HTTP POST requests from React to a backend API using fetch() which comes bundled with all modern browsers.
Other HTTP examples available:
- React + Fetch: GET, PUT, DELETE
- React + Axios: GET, POST, PUT, DELETE
- Angular: GET, POST, PUT, DELETE
- Vue + Fetch: GET, POST, PUT, DELETE
- Vue + Axios: GET, POST
- Blazor WebAssembly: GET, POST
- Axios: GET, POST, PUT, DELETE
- Fetch: GET, POST, PUT, DELETE
Simple POST request with a JSON body using fetch
This sends an HTTP POST request to the Reqres api which is a fake online REST api that includes a /api/posts route that responds to POST requests with the contents of the post body and an id property. The id from the response is assigned to the react component state property postId so it can be displayed in the component render() method.
componentDidMount() {
// Simple POST request with a JSON body using fetch
const requestOptions = {
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({ title: 'React POST Request Example' })
};
fetch('https://reqres.in/api/posts', requestOptions)
.then(response => response.json())
.then(data => this.setState({ postId: data.id }));
}
Example React component at https://stackblitz.com/edit/react-http-post-request-examples-fetch?file=App/PostRequest.jsx
POST request using fetch with React hooks
This sends the same POST request from React using fetch, but this version uses React hooks from a function component instead of lifecycle methods from a traditional React class component. The useEffect React hook replaces the componentDidMount lifecycle method to make the HTTP POST request when the component loads.
The second parameter to the useEffect React hook is an array of dependencies that determines when the hook is run, passing an empty array causes the hook to only be run once when the component first loads, like the componentDidMount lifecyle method in a class component. For more info on React hooks see https://reactjs.org/docs/hooks-intro.html.
useEffect(() => {
// POST request using fetch inside useEffect React hook
const requestOptions = {
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({ title: 'React Hooks POST Request Example' })
};
fetch('https://reqres.in/api/posts', requestOptions)
.then(response => response.json())
.then(data => setPostId(data.id));
// empty dependency array means this effect will only run once (like componentDidMount in classes)
}, []);
Example React hooks component at https://stackblitz.com/edit/react-http-post-request-examples-fetch?file=App/PostRequestHooks.jsx
POST request using fetch with async/await
This sends the same POST request from React using fetch, but this version uses an async function and the await javascript expression to wait for the promises to return (instead of using the promise then() method as above).
async componentDidMount() {
// POST request using fetch with async/await
const requestOptions = {
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({ title: 'React POST Request Example' })
};
const response = await fetch('https://reqres.in/api/posts', requestOptions);
const data = await response.json();
this.setState({ postId: data.id });
}
Example React component at https://stackblitz.com/edit/react-http-post-request-examples-fetch?file=App/PostRequestAsyncAwait.jsx
POST request using fetch with error handling
This sends a POST request from React to an invalid url on the api then assigns the error to the errorMessage component state property and logs the error to the console.
The fetch() function will automatically throw an error for network errors but not for HTTP errors such as 4xx or 5xx responses. For HTTP errors we can check the response.ok property to see if the request failed and reject the promise ourselves by calling return Promise.reject(error);. This approach means that both types of failed requests - network errors and http errors - can be handled by a single catch() block.
componentDidMount() {
// POST request using fetch with error handling
const requestOptions = {
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({ title: 'React POST Request Example' })
};
fetch('https://reqres.in/invalid-url', requestOptions)
.then(async response => {
const isJson = response.headers.get('content-type')?.includes('application/json');
const data = isJson && await response.json();
// check for error response
if (!response.ok) {
// get error message from body or default to response status
const error = (data && data.message) || response.status;
return Promise.reject(error);
}
this.setState({ postId: data.id })
})
.catch(error => {
this.setState({ errorMessage: error.toString() });
console.error('There was an error!', error);
});
}
Example React component at https://stackblitz.com/edit/react-http-post-request-examples-fetch?file=App/PostRequestErrorHandling.jsx
POST request using fetch with set HTTP headers
This sends the same POST request again from React using fetch with a couple of extra headers set, the HTTP Authorization header and a custom header My-Custom-Header.
componentDidMount() {
// POST request using fetch with set headers
const requestOptions = {
method: 'POST',
headers: {
'Content-Type': 'application/json',
'Authorization': 'Bearer my-token',
'My-Custom-Header': 'foobar'
},
body: JSON.stringify({ title: 'React POST Request Example' })
};
fetch('https://reqres.in/api/posts', requestOptions)
.then(response => response.json())
.then(data => this.setState({ postId: data.id }));
}
Example React component at https://stackblitz.com/edit/react-http-post-request-examples-fetch?file=App/PostRequestSetHeaders.jsx
Update History:
- 22 Apr 2021 - Replaced JSONPlaceholder API with Reqres API in examples because JSONPlaceholder stopped allowing CORS requests
- 01 Feb 2020 - Created fetch POST request examples
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