JavaScript, React

ES2017 async/await with fetch in Redux (No Callback Hell anymore)

When we need to use third party API or any REST API in our web app, we need to wait for the response coming from the server.
Then in the success callback , we use that data and do other operations.And if we have more REST calls, we all know that it could end up being a Callback Hell

But if we use ES2017 async/await syntax , we can write our code as clean as possible with minimum lines of code.

Basic example of async/await is like below-

function resolveAfter2Seconds() {
  return new Promise(resolve => {
    setTimeout(() => {
      resolve('resolved');
    }, 2000);
  });
}

async function asyncCall() {
  console.log('calling');
  var result = await resolveAfter2Seconds();
  console.log(result);
  // expected output: "resolved"
}

asyncCall();

here var result = await resolveAfter2Seconds(); will wait to resolve the Promise and assign the returned data to `result` variable.
It seems like its executing the code line by line though it has asynchronous operation , which is awesome!

As of now , we know basic of async/wait , now we will use this inside redux ActionCreator. But first we will see how the code looks like without using async/await.
So our action creator code is –

export const getSpeakers = () => (dispatch, getState) => {
  return fetch(`${API_SERVER}/speakers`)
    .then(
      response => response.json(),
      error => {
        console.log("No! error occured.", error);
        throw error;
      }
    )
    .then(speakers => {
      console.log("speakers success", speakers);
      dispatch(saveSpeakers(speakers));
    })
    .catch(error => {
      console.log("Return Error by throwing", error);
      throw error;
    });
};

So here ^ is our action creator named `getSpeakers` which calls one REST API endpoint and then dispatch the speakers to the redux store.Here we can see we need to chain with `then`, `catch` etc which make the code a bit messy and hard to understand.

Now we will use async/await with fetch and will make our code good looking

export const getSpeakers = () => async (dispatch, getState) => {
  try {
    const response = await fetch(`${API_SERVER}/speakers`);
    const speakers = await response.json();
    console.log("speakers success", speakers);
    dispatch(saveSpeakers(speakers));
  } catch (error) {
    console.log("throwing Error", error);
    throw error;
  }
};

Here , we have added try/catch so that if any error happens, we can catch and take our decision what we want to do. Here in this case , I have just thrown the error, but we can dispatch another FAILURE action.
Ah , that made our code smaller,cleaner and easy to understand!

Cheers!

Standard
React

Single Page Application (SPA) with React

Let’s talk about ReactJS today and how we can easily create a Single Page Application (SPA) with React. For routing , I will use a library called react-router . For this post, I will use v3.x . I will write another article based on v4.x.

ReactJS is really popular now a days , and developers are using ReactJS and react-router for creating SPAs .

react spa

I will use 4 Routes for my sample SPA with React. For this , I created 4 Components which represent 4 different routes.
Then we can import 4 Components on index.js file like below-

import App from './App/Components/App.jsx';
import Profile from './App/Components/Profile.jsx';
import Contact from './App/Components/Contact.jsx';
import Error from './App/Components/404.jsx';

Our `404.jsx` is actually for 404 or not found route.

We can use those Components to create out SPA routing with react-router-

<Router history={hashHistory}>
    <Route path="/" component={App}>
        <Route path="/profile" component={Profile}/>
        <Route path="/contact" component={Contact}/>
        <Route path="*" component={Error}/>
    </Route>
  </Router>

The full Code is available here https://github.com/destromas1/react-spa

Cheers!

Standard
JavaScript, React

Play with React for beginners with react-basic-starter

I have been working with React for long time now . But as I was not regular in writing , that’s why I have never written a single post on React.

This would be officially my first ReactJS post , and I know I am late.

react-basic-starter

Its 2017 . There are lot of articles published on Web . Facebook has created a tool for React developers called create-react-app which is awesome for starting any new react based project. But What I feel , if anyone is a fresher in React , then its a bit more than the skill level.Also I feel React Developers should learn a bit of Webpack , thats why I added a simple Webpack Config for building react code.

This post actually tries to help a react fresher to start creating his/her first React sample component and do some fun in his Bedroom playground.

module.exports = {
  entry: './index.js',
  output: { path: __dirname, filename: 'bundle.js' },
  module: {
    loaders: [
      {
        test: /.jsx?$/,
        loader: 'babel-loader',
        exclude: /node_modules/,
        query: {

        }
      }
    ]
  },
};

The upper code snippet is available inside webpack.config.js file and It will build the React Code and JSX and create a file called `bundle.js`

Inside our `index.html` file we have included this bundle to load as script.

<script src="bundle.js"></script>

Our simple component is available on `App.jsx` file which has only one H1 inside.

export default class App extends React.Component {
  render() {
    return(
      <div>
        <h1>React Basic Starter</h1>
      </div>
    )
  }
};

Full code is available at my Github Repo https://github.com/destromas1/react-basic-starter

Cheers!

Standard