Create React App with TypeScript

FEBRUARY 6, 2020

npx and create-react-app make it easy to create a new app running React and TypeScript.

npx create-react-app my-app --template typescript

Then you go into the folder and run the app.

cd my-app
npm start

You can create a JavaScript (non-TypeScript) app by removing the last bit—--template typescript. And you can also run the app with yarn start.

If, as I was, you're not getting the app working, you might have an older global installation of create-react-app. In my case I installed it with npm install -g create-react-app (which I could verify by running create-react-app -V on the Terminal. To make sure npx uses the latest version of create-react-app you need to uninstall the global version installed with npm.

npm uninstall -g create-react-app

Before you go

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[Solved] Invariant Violation: Target container is not a DOM element

FEBRUARY 25, 2019

In trying to export my React's Redux store from index.tsx to be used somewhere else outside of the React application, I was getting an Invariant Violation: Target container is not a DOM element error while running Jest tests (with Enzyme and Webpack) in the App component (App.tsx).

I found a solution to this error for my use case, which was using the same Redux store React is using outside of React.

The error

The initial code that didn't work when testing React looked like this.

// index.tsx

import * as React from "react";
import { render } from "react-dom";
import { Provider } from "react-redux";
import { applyMiddleware, compose, createStore } from "redux";
import App from "./components/App";
import { rootReducer } from "./store/reducers";
import { initialState } from "./store/state";

const middlewares = [];

export const store = createStore(
    rootReducer,
    initialState,
    compose(applyMiddleware(...middlewares)),
);

render(
    <Provider store={store}>
        <App />
    </Provider>,
    document.getElementById("root"),
);

The solution

Separate the Redux store logic into a new file named store.ts, then create a default export (to be used by index.tsx, i.e., the React application) and a non-default export with export const store (to be used from non-React classes), as follows.

// store.ts

import { applyMiddleware, compose, createStore } from "redux";
import logger from "redux-logger";
import { rootReducer } from "./store/reducers";
import { initialState } from "./store/state";

const middlewares = [];

export const store = createStore(
    rootReducer,
    initialState,
    compose(applyMiddleware(...middlewares)),
);

export default store;

// updated index.tsx

import * as React from "react";
import { render } from "react-dom";
import { Provider } from "react-redux";
import App from "./components/App";
import store from "./store";

render(
    <Provider store={store}>
        <App />
    </Provider>,
    document.getElementById("root"),
);

Using the Redux store in non-React classes

// MyClass.ts

import { store } from "./store"; // store.ts

export default class MyClass {
  handleClick() {
    store.dispatch({ ...new SomeAction() });
  }
}