Frequently Asked Questions

In addition to the questions below, see the Exponent AMA on Hashnode for more common questions and answers.

How much does Exponent cost?

Exponent is free.

Our plan is to keep it this way indefinitely.

Exponent is also open source, so you don’t have to trust us to stick to that plan.

We might eventually charge money for services built on top of Exponent or for some kind of premium level of support and consulting.

How do you make money if Exponent is free?

Right now, we don’t make any money. We have a small team that just wants to work on this, and we keep our expenses low and are mostly self-funded. We can keep working on this project like this for a while as long as there are people who want to use it.

We think if we can make Exponent good enough, we can eventually help developers make money, and we could take a cut of that. This could be through helping them collect money from people using their software, or by helping them place ads in their apps, or other things. We don’t really have a clear plan for this yet; our first priority is just to make Exponent work really well and be as popular as possible.

What is the difference between Exponent and React Native?

Exponent is kind of like Rails for React Native. Lots of things are set up for you, so it’s quicker to get started and on the right path.

With Exponent, you don’t need Xcode or Android Studio. You just write JavaScript using whatever text editor you are comfortable with (Atom, vim, emacs, Sublime, VS Code, whatever you like). You can run XDE (our desktop software) on Mac, Windows, and Linux.

Here are some of the things Exponent gives you out of the box that work right away:

• Support for iOS and Android

  You can use apps written in Exponent on both iOS and Android right out of the box. You don’t need to go through a separate build process for each one. Just open any Exponent app in the Exponent Developer app from the App Store on either iOS or Android (or in a simulator or emulator on your computer).

• Push Notifications

  Push notifications work right out of the box across both iOS and Android, using a single, unified API. You don’t have to set up APNS and GCM/FCM or configure ZeroPush or anything like that. We think we’ve made this as easy as it can be right now

• Facebook Login

  This can take a long time to get set up properly yourself, but you should be able to get it working in 10 minutes or less on Exponent.

• Instant Updating

  All Exponent apps can be updated in seconds by just clicking Publish in XDE. You don’t have to set anything up; it just works this way. If you aren’t using Exponent, you’d either use Microsoft Code Push or roll your own solution for this problem

• Asset Management

  Images, videos, fonts, etc. are all distributed dynamically over the Internet with Exponent. This means they work with instant updating and can be changed on the fly. The asset management system built-in to Exponent takes care of uploading all the assets in your repo to a CDN so they’ll load quickly for anyone.

  Without Exponent, the normal thing to do is to bundle your assets into your app which means you can’t change them. Or you’d have to manage putting your assets on a CDN or similar yourself.

• Easier Updating To New React Native Releases

  We do new releases of Exponent every few weeks. You can stay on an old version of React Native if you like, or upgrade to a new one, without worrying about rebuilding your app binary. You can worry about upgrading the JavaScript on your own time.

But no native modules…

The most limiting thing about Exponent is that you can’t add in your own native modules. Continue reading the next question for a full explanation.

How do I add custom native code to my Exponent project?

Right now, Exponent doesn’t support custom native code, including third-party libraries which require custom native components. In an Exponent project, you never write native code—only pure JS.

In our SDK, we give you a large set of commonly desired, high-quality native modules. However, if you need something very custom—like on-the-fly video processing or low level control over the Bluetooth radio to do a firmware update—then Exponent won’t work for you and you should instead use regular React Native.

You can do more in just JavaScript than you realize—and in fact, we recommend doing as much in JS as possible, since it will immediately work across both platforms and is less fragile—so you shouldn’t need to include UI widgets that are written as native modules (there are almost always good pure JavaScript alternatives that are better).

We’re always improving our SDK and its native capabilities. Tell us about what’s missing, and we’ll try to add what you need if we think there are other people who would use it too. (Tweet @ us or join our Slack or e-mail support@getexponent.com).

Lastly, Exponent is open source, so you always have the option of forking our native code or contributing to it. Please get in touch on our Slack if you’re interested in sending a pull request!

Is Exponent similar to React for web development?

Exponent and React Native are similar to React. You’ll have to learn a new set of components (View instead of div, for example) and writing mobile apps is very different from websites; you think more in terms of screens and different navigators instead of separate web pages, but much more your knowledge carries over than if you were writing a traditional Android or iOS app.

How do I publish my Exponent project? Can I submit it to the app stores?

With Exponent you have two options to publish your project. The first is to create a standalone app that you submit to Apple and Google’s app stores. It’s easy to build standalone apps with Exponent; see our guide to learn how to create the iOS IPA and Android APK binaries. Apple charges $99/year to publish your app in the App Store and Google charges a $25 one-time fee for the Play Store.

The second option is to publish your project using Exponent. Anyone with the Exponent app can then open your project if they have the URL for it. This option is free and is wonderful for sharing your project with friends. These two options aren’t mutually exclusive so you can choose both of them.

Can I use Exponent with Relay?

You can! Update your .babelrc you get on a new Exponent project to the following:

{
  "presets": [
    "react-native-stage-0/decorator-support",
    {"plugins": ["./pathToYourBabelRelayPlugin/babelRelayPlugin"]}
  ],
  "env": {
    "development": {
      "plugins": ["transform-react-jsx-source"]
    }
  }
};

Substitute ./pathToYourBabelRelayPlugin with the path to your Relay plugin.

How do I get my existing React Native project running with Exponent?

We provide a conversion tool for this:

• Make sure you have the Exponent command line utility: npm install -g exp
• From your project directory, run exp convert

We will do anything that we can do to convert your project automatically, and we’ll provide followup instructions for steps you will have to perform manually.

Note that the results of this tool might vary widely depending on what your project contains. If you have similar native module dependencies to what is exposed through the Exponent SDK, this process shouldn’t take more than a few minutes (not including npm install time). Please feel free to ask us questions if you run into any issues.