The coronavirus crisis is having a huge impact on young people with existing mental health conditions.

Since time immemorial, a village in West Bengal has paid tribute to Shiva by self-inflicting pain. This year coronavirus put a stop to it.

Rob thought he was helping a refugee girl and her father as they struggled to get to the UK. But he found out it was all a lie.

Philipp travels to a conference on men’s issues in Chicago, shedding light on the controversial movement.

Disability and sex is a topic around which there are a lot of misconceptions, but what do disabled people think when people get awkward talking about sex with them?

Growing up as a Hasidic Jew, Abby Stein had no idea trans people existed - she just felt sure she was a girl.

Cheese shops and gun stores are among the services still open in locked down places around the world.

A petition calling for maternity leave to be extended due to coronavirus has attracted many signatures.

Inside the Nicaraguan boxing event that caught the world's attention during the pandemic.

The 211 machines were purchased from a US firm, Mexico's foreign minister said.

Magaly Contreras has spent nine months in a Tijuana shelter and is worried about her future.

After writing my post a few months ago on building your own redux app, I have been asked a couple times to write a guide on creating redux middleware and how it works. This will be a quick post on how you can acheive anything with your own middleware!

##Basic middleware

const customMiddleware = store => next => action => {
  if(action.type !== 'custom') return next(action)
  //do stuff!
}

Applying it:

import { createStore, applyMiddleware, } from 'redux'
import reducer from './reducer'
import customMiddleware from './customMiddleware'

const store = createStore(
  reducer,
  applyMiddleware(customMiddleware)
)

Whaaa? store => next => action => I know that looks confusing. Essentially you are building a chain of functions, it will look like this when it gets called:

//next looks something like this:
let dispatched = null
let next = actionAttempt => dispatched = actionAttempt 

const dispatch = customMiddleware(store)(next)

dispatch({
  type: 'custom',
  value: 'test'
})

All you are doing is chaining function calls and passing in the neccesary data. When I first saw this I was confused a little due to the long chain, but it made perfect sense after reading the article on writing redux tests.

So now that we understand how those chained functions work, let’s explain the first line of our middleware.

if(action.type !== 'custom') return next(action)

There should be some way to tell what actions should go through your middleware. In this example, we are saying if the action’s type is not custom call next, which will pass it to any other middleware and then to the reducer.

##Doing Cool stuff

The official guide on redux middleware covers a few examples on this, I’m going to try to explain it in a more simple way.

Say we want an action like this:

dispatch({
  type: 'ajax',
  url: 'http://api.com',
  method: 'POST',
  body: state => ({
    title: state.title
    description: state.description
  }),
  cb: response => console.log('finished!', response)
})

We want this to do a post request, and then call the cb function. It would look something like this:

import fetch from 'isomorphic-fetch'

const ajaxMiddleware = store => next => action => {
  if(action.type !== 'ajax') return next(action)
  
  fetch(action.url, {
    method: action.method,
    body: JSON.stringify(action.body(store.getState()))
  })
  .then(response => response.json())
  .then(json => action.cb(json))
}

It’s pretty simple really. You have access to every method redux offers in middleware. What if we wanted the cb function to have access to dispatching more actions? We could change that last line of the fetch function to this:

.then(json => action.cb(json, store.dispatch))

Now in the callback, we can do:

  cb: (response, dispatch) => dispatch(newAction(response))

As you can see, middleware is very easy to write in redux. You can pass store state back to actions, and so much more. If you need any help or if I didn’t go into detail enough, feel free to leave a comment below!

Without any modifications, React is really fast as-is. There are, however, a few things that you can do to improve performance. While working at HelloSign, I discovered some quick fixes that made our apps incredibly snappy. With these simple changes, I was able to reduce render time from over 3000 milliseconds to less than 200 milliseconds.

Without any modifications, React is really fast as-is. There are, however, a few things that you can do to improve performance. While working at HelloSign, I discovered some quick fixes that made our apps incredibly snappy. With these simple changes, I was able to reduce render time from over 3000 milliseconds to less than 200 milliseconds.

Editor’s Note:

Check out our upcoming React University Workshops. Our next workshop, React 2016, will be held on April 23 at Microsoft Reactor in San Francisco and will offer a deep dive into creating modern Single-Page Applications (SPA) using React, Redux, React Router, Immutable.js, and Webpack. Also, if you’re interested in learning the basics about what it takes to be a Data Visualization Engineer, check out React and D3.

Introduction

HelloSign is a cloud-based electronic signature tool founded in 2010. As you can imagine, HelloSign is a very JavaScript-heavy codebase. A lot of client-side behavior is necessary to create a rich signing experience. Lately, we’ve moved much of our codebase toward React. In fact, in many places we’ve broken up our codebase into several single-page applications written in React.

Although the HelloSign team was happy with React’s performance before I initially joined the project, I quickly found some low-hanging fruit that could improve runtime speed. Here are the steps you should take to see similar improvements in your own applications.

Create a Baseline Performance Measurement

Before you begin, you should take a baseline measurement. Optimizations are meaningless if you can’t verify the results of your modifications.

Thankfully, Chrome has excellent developer tools to help. One, little-used feature of Chrome’s DevTools is the “Timeline” tool. It allows you to record and analyze all activity in your application. You can record interactions on the page, locate potential memory leaks, measure the total time it takes to perform a task, and identify areas of potential jank. Best of all, the results can be recorded for comparison with your final benchmark.

There’s actually a really awesome video on Chrome’s DevTools that goes into detail about the “Timeline” feature. You can view it here.

We chose to measure the time elapsed between the initial paint of our signer page to the final rendering of the entire page. The initial download of our bundles still needs some optimization, but we’re neither going to mess with nor measure this parameter. It’s fairly easy and consistent to test render time rather than trying to click areas around the page and trying to measure its performance in a repeatable way. Then, all we needed to do was to go to the signer page, open Chrome’s DevTools “Timeline” tab, and refresh the page.

As a side note, make sure that when performing this test, the “Paint” and “Screenshots” boxes are checked so that you can see what the user sees as the page is being rendered.

After all that, we determined that our rendering time from initial paint was a little over 3 seconds. Much too long. Luckily, there was little we had to do to make this quite a bit faster.

Set NODE_ENV to Production

This step is easy to get wrong, even if you are well-informed. React’s documentation provides an overview, but doesn’t provide many specifics. React has great developer warnings and error checking, but these are only intended for development; if you take a look at React’s source code, you’ll see a lot of if (process.env.NODE_ENV != 'production') checks. This is running extra code that is not needed by the end user, not to mention that calling process.env.NODE_ENV is extremely slow. For production environments, we can remove all this unnecessary code. Just keep in mind that you don’t want to do this in development because it will remove all those helpful developer warnings.

If you’re using Webpack, you can use DefinePlugin to replace all instances of process.env.NODE_ENV with 'production', and then use the UglifyJsPlugin to remove all the dead code that no longer runs. Here’s a sample setup that you might use:

// webpack.config.js
  ...
  plugins: [
    new webpack.DefinePlugin({
      // A common mistake is not stringifying the "production" string.
      'process.env.NODE_ENV': JSON.stringify('production')
    }),
    new webpack.optimize.UglifyJsPlugin({
      compress: {
        warnings: false
      }
    })
  ]
  ...

React Constant and Inline Elements Transforms

React 0.14 introduced support for certain transpile time optimizations with Constant and Inline Element Babel Transforms. React Constant Elements treats JSX elements as values and hoists them to a higher scope. In other words, it hoists static elements and thereby reduces calls to React.createClass. React Inline Elements converts JSX elements into the object literals that they eventually return. Again, this minimizes the runtime calls to React.createClass.

The implementation is rather simple. We added our Babel configuration in our package.json file:

// package.json
  ...
  "babel": {
    "env": {
      "production": {
        "plugins": [
          "transform-react-constant-elements",
          "transform-react-inline-elements"
        ]
      }
    }
  },
  ...

Final Measurement / Conclusion

Lastly, you’ll want to run the benchmark again and compare it with that saved benchmark from before these optimizations. As you can see, the total runtime profile ends 200ms after initial paint! That’s 15 times faster!

React Native continues on a development spree in late 2016. With an ambitious two-week release cycle, the framework makes rapid progress towards feature and performance parity with its native Android and iOS equivalents. At the same time, these quick release periods frequently introduce breaking changes, difficulty with setup, and challenges with basic configuration.

Enter Exponent, a tool that promises easier setup, development, and deployment of React Native applications. Rather than being a replacement for React Native, as it is sometimes confused, Exponent augments React Native by dramatically simplifying the development and deployment processes. Whereas basic setup with an Android environment to develop with React Native can take over an hour by hand, even for experienced engineers, Exponent shortens the time to start to “Hello World” to a handful of minutes.

React Native continues on a development spree in late 2016. With an ambitious two-week release cycle, the framework makes rapid progress towards feature and performance parity with its native Android and iOS equivalents. At the same time, these quick release periods frequently introduce breaking changes, difficulty with setup, and challenges with basic configuration.

Enter Exponent, a tool that promises easier setup, development, and deployment of React Native applications. Rather than being a replacement for React Native, as it is sometimes confused, Exponent augments React Native by dramatically simplifying the development and deployment processes. Whereas basic setup with an Android environment to develop with React Native can take over an hour by hand, even for experienced engineers, Exponent shortens the time to start to “Hello World” to a handful of minutes.

Exponent’s prime feature is revealed as it’s namesake IDE. The Exponent IDE is development platform for not only developing apps to test in their respective environment simulators, but also simplifies testing them on real devices.

One of the cofounders of Exponent, Charlie Cheever, agreed to answer a few questions about Exponent and its purpose in the community.

Hi, Charlie. Congrats on the release of Exponent! One of the toughest aspects of Exponent is understanding what its purpose is. What is the primary goal of Exponent?

Thanks :)

Before I worked on mobile software, I spent about 15 years making websites. When I started working on the Quora iPhone app and Android app, it felt like time traveling back to 1993. So many things to worry about that have nothing to do with the product you want to build.

One thing we’re trying to do with Exponent is making it as easy to develop native mobile apps as it is to make websites, or even easier! I think about how I learned to build software as a kid–making games on my TI-85 and making Hypercard stacks–and I want to make it so that the middle school kids of today can make cool stuff for themselves and their friends.

Basic environment setup of the iOS and Android simulators for developing React Native apps is commonly cited as a headache by new developers. What does Exponent do to alleviate this pain?

The biggest thing that Exponent does is take care of everything related to native code for you. So you don’t need to know Swift/Obj-C/Java or even have Xcode or Android Studio to be able to write React Native apps. You write just JavaScript and Exponent has everything else already setup for you.

Since you don’t write any native code with Exponent, just JavaScript, Exponent has a lot of the most popular native modules built in. Native maps, push notifications, Facebook and Google login, camera and camera roll access, contacts, TouchID, and a native video player are all included among other things. We’re always adding more of these as well. We just added full OpenGL support last week and did a game jam and made some mini games with it and are adding sound soon.

We sometimes talk about Exponent as being like Rails for React Native. You could write a website in Ruby on your own. but Rails sets up a bunch of sensible things right off that bat that work together in a coherent way and we kind of do the same thing for React Native. Exponent includes instant app updating as a default, so you can deploy new code and assets with one command in seconds, even faster than most websites can be deployed.

Even after getting set up with the Android and iOS simulators, testing a React Native app on a real phone can still be a challenge. How does Exponent make it easier to share apps in progress with would-be users?

You can actually open any Exponent project that you’re working on in our development app right away. When you develop with Exponent, you get a URL for your project, and you can open that URL on any phone with the Exponent developer app which you can download from the iOS App Store or Google Play Store. You don’t need to jack your phone into your computer–just open the URL.

Another really cool thing about this is that, if you’re working with someone else, you can just send them the URL and they can open it on their phone as well, even if they are halfway around the world.

We’ve done a bunch of work to make this pretty nice, like having console.log work even if the phone running your code isn’t plugged into your computer. And you can, of course, open your project on the iOS Simulator or an Android Emulator as well if you prefer.

I know you mentioned a lot of people have trouble getting React Native setup on Android especially. With Exponent, every project works on both iOS and Android from the start and you never have to deal with Android Studio, so the process of getting going is much easier.

What type, or genre, of application would be a good fit with React Native and Exponent?

I would actually use React Native for almost any mobile app at this point. Doing development the traditional way (writing Swift/Java/Obj-C code) is just too hard to iterate on when you consider the slowness of the code-compile-copy-run loop and the fact that you have to write your app twice (and then keep it in sync!). The other thing that is an absolutely huge deal here but is sometimes overlooked is the layout engine. It’s much easier to build and change a layout in React Native’s Flexbox than any of the UI libraries that I’ve seen for Java/Swift/Obj-C.

And if you need to do something really intense, like Snapchat live video filters, you can just write your own code as a native module and write the rest of your app in JS.

I would use Exponent for anything I could because it just saves a lot of time and headaches since you don’t need to deal with Android Studio or Xcode. Some people don’t know that you can turn an Exponent project into an app store app for iOS or for Android with just one command.

In general, Exponent will work for you in pretty much every case where just having a mobile website is one of the things that you’re considering. The features are pretty equivalent except that Exponent apps feel like native apps and mobile apps still feel like mobile web apps.

The main reason not to use Exponent is if you have some custom native code that you need that isn’t included with Exponent. The most common reasons that people can’t use Exponent are if they need use Bluetooth or HealthKit or something else low level that isn’t built in to Exponent; or if they need to integrate into an existing project (though we are working right now on a solution that will let you do this).

The exception to all this is games. If you are making a mobile game, Unity is probably the best choice for you. But we did add OpenGL support to Exponent recently and had a game jam and I was surprised at how good some of the entries were, so I think that might change.

TL;DR: For apps that aren’t games, always use React Native (if you need to do something super custom, just do it as a native module). If you can, use Exponent (you can most of the time but check our docs to make sure we’re not missing anything you need).

One aspect of React Native that seems to be undergoing constant flux is its solution for navigation. Between the built in Navigators and open source solutions, do you have any thoughts on an ideal solution for navigation?

Short version: I think you should use Ex-Navigation that Adam Miskiewicz (skevy) and Brent Vatne on our team wrote. Skevy in particular has been thinking about navigation in mobile apps and React Native for a long time. Using Ex-Navigation is definitely a better idea than Navigator or NavigatorIOS.

To make things confusing, there is also NavigatorExperimental (yes, that’s different from Ex-Navigation) and ExNavigator (which was made by James Ide and Ex-Navigation is based on). The good news is that everyone working on these problems got together and decided to merge them all together. I don’t know how long that is going to take but it will probably be released sometime in the next few months under the name React Navigation, and that should unify everyone’s efforts!

There is also this other school of thought where some people like to use the platform-specific native code for navigation which is the approach that the Wix Navigator uses. I have a strong personal view that its preferable to write UI components like this in JS because I actually think you want your app to be the same across iOS and Android (they are both just black rectangles with touch screens!) and JS tends to make your code more composable and customizable.

Use Ex-Navigation and keep an eye out for React Navigation! Use JS instead of native for this UI code!

Given the increasingly fast development and deployment times, handling API setup for dealing with data is becoming a large obstacle to React Native apps. Do you have any thoughts about the use of Backend-As-A-Service solutions like Firebase compared to rolling your own API with Node/Express, Rails, or similar?

I don’t have a strongly held view on this right now. There are so many solutions that fit the use cases of people with different needs. We’re seeing things getting easier and easier in every direction that you look.

If you want to write your own code and you’re using JS, you can use something like Zeit’s new now stuff to deploy essentially instantly. If you want a more general purpose solution, Heroku is also really easy. And then of course there is AWS and Google Cloud, etc.

It’s trivially easy for React Native apps to communicate with essentially any backend that uses HTTP/JSON since fetch and JSON.parse are built-in.

If you don’t want to write any code, it seems like Firebase has become the most popular solution since Parse announced its shutdown. One nice thing about Firebase is that you can use their hosted database stuff with React Native using just JS, which means it works just fine with Exponent. Someone wrote up a guide to how to do this here: https://gist.github.com/sushiisumii/d2fd4ae45498592810390b3e05313e5c

Longer term, it seems like something like GraphQL/Relay should become really popular, but that stuff is too hard to setup and use still to be mainstream just yet. I’m not sure whether it will be GraphQL/Relay maturing and getting revised that wins or something else that is slightly different and easy to think about as a developer that comes and beats it, but directionally, it’s definitely right. We built something like this at Quora and it saved a ton of development time.

I would just use whatever you are most comfortable with – almost anything will work! React Native is really similar to the the web in terms of its client capabilities and so I would just think about a React Native or Exponent app as being mostly like a website.

One of the most common problems that I run into when using Redux is trying to figure out why an action is not being captured by a reducer. For someone just getting starting with Redux, debugging this issue can be especially overwhelming because of how Redux manages data flow. So before you start pouring over configuration code, or the logic contained in your action creators and reducers, please, make sure your action types are defined and spelled correctly.

One of the most common problems that I run into when using Redux is trying to figure out why an action is not being captured by a reducer. For someone just getting starting with Redux, debugging this issue can be especially overwhelming because of how Redux manages data flow. So before you start pouring over configuration code, or the logic contained in your action creators and reducers, please, make sure your action types are defined and spelled correctly.

In any application that I have built, most bugs that I have run into are simply due to typos. However, the solution to this particular problem is harder to spot because no errors are raised when the application is run. Take a look at the snippet below.

// actionTypes.js

export const FETCH_FILE_REQUEST = 'fetch_file_request';
export const FETCH_FILE_SUCCESS = 'fetch_file_success';
export const FETCH_FILE_FAIL = 'fetch_file_fail';


// filesReducer.js

import {
  FETCH_FILE_REQUEST,
  FETCH_FILE_SUCESS,
  FETCH_FILE_FAIL
} from '../actions/actionTypes';

const filesReducer = (state = {}, action) => {
  switch (action.type) {
    case FETCH_FILE_SUCESS:
      return { ...state, file: action.payload };
    default:
      return state;
  }
}

export default filesReducer;

Assuming we dispatched an action with type FETCH_FILE_SUCCESS, the filesReducer should catch the action before the default case is returned. But what if that is not happening? Where do we start the debugging process. There does not appear to be anything wrong with the code in the reducer; the action type was imported and matches the case in the switch statement. There are no errors in the browser. Where is the issue?

You may have noticed that I misspelled SUCCESS in filesReducer.js, but the reason this can be hard to catch is because importing undefined types does not cause an error, so when we import FETCH_FILE_SUCESS, its value is actually undefined, so our reducer always hits the default case.

It would be nice if the existing import/export system could help us catch this. Unfortunately, since action types are just strings, validating their existence is challenging. Luckily, we have another option.

Enter Proxies

Proxies are a feature of ES2015 that allow us to customize operations on a object. They can be used in many different ways, and you can find some useful examples here and here. For our problem, this example from Mozilla looks promising:

let validator = {
  set: function(obj, prop, value) {
    if (prop === 'age') {
      if (!Number.isInteger(value)) {
        throw new TypeError('The age is not an integer');
      }
      if (value > 200) {
        throw new RangeError('The age seems invalid');
      }
    }

    // The default behavior to store the value
    obj[prop] = value;

    // Indicate success
    return true;
  }
};

let person = new Proxy({}, validator);

person.age = 100;
console.log(person.age); // 100
person.age = 'young'; // Throws an exception
person.age = 300; // Throws an exception

So if proxies can be used to validate that properties assigned to an object are of a certain type and value, we should definitely be able to ensure that our action types are never undefined, or else throw an error that will be easy for us to fix. Let’s refactor our actionTypes.js file.

// actionTypes.js

const types = {
  FETCH_FILE_REQUEST: 'fetch_file_request',
  FETCH_FILE_SUCCESS: 'fetch_file_success',
  FETCH_FILE_FAIL: 'fetch_file_fail'
}

const typeValidator = {
  get(obj, prop) {
    if (obj[prop]) {
      return prop;
    } else {
      throw new TypeError(`${prop} is not a valid action type`);
    }
  }
}

module.exports = new Proxy(types, typeValidator);

First, we define a object containing all our action types. Then we define our validator handler typeValidator. The get method inside our handler is called a trap, and provides access to the properties of a object. If the property we are looking for, an action type, in this case, exists in the types object, return that prop, unmodified. Otherwise, throw an error because the prop does not exist.

Finally, export a new proxy, passing the types object as the target and the typeValidator as the handler. However, it is important to note that the ES2015 module system does not work well with proxies, so module.exports and require() must be used for exporting and importing the types.

Barely any code needs to change in the reducer and action creator files, but in order for the action types to be imported successfully, we just need couple lines of code in a new file:

// actionTypesProxy.js

export const {
  FETCH_FILE_REQUEST,
  FETCH_FILE_SUCCESS,
  FETCH_FILE_FAIL,
} = require('./actionTypes');

// in the reducer and action creator files
// change '../actions/actionTypes' to
// '../actions/actionTypesProxy'

By creating a proxy to verify the existence of an action type, we no longer have to worry about correctly naming a property upon import because an error will be thrown in the browser console as soon as the application starts. So, reduce the number headaches you get when developing an application using Redux and start using proxies.

Interested in learning how to build applications using Redux with ReactJS. Check out this online course! Modern React with Redux

Bruno Coelho speaks to ​FIFA.com ​after his side fell at the final hurdle, defeated by Argentina in the semi-finals of the FIFA Futsal World Cup Colombia 2016.