React: "Module not found: Can't resolve" Path error

Since the file is in same directory

If it’s not default export You should import it like

  import { Typography} from './Typography'; 

If default export, you should import it like

 import Typography from './Typography'; 

Module not found: Can't resolve <module name> in <file path>

I ran

npm install
npm build
npm start

Now the module has been installed under dependencies in package.json, and my web app starts in http://localhost:3000/, the port specified in launch.json.

React utilizes features of modern JavaScript for many of its patterns. Its biggest departure from JavaScript comes with the use of JSX syntax. JSX extends JavaScript's syntax so that HTML-like code can live alongside it. For example:

const heading = <h1>Mozilla Developer Network</h1>;

Suppose we wanted to wrap our heading in a <header> tag, for semantic reasons? The JSX approach allows us to nest our elements within each other, just like we do with HTML:

const header = (
  <header>
    <h1>Mozilla Developer Network</h1>
  </header>
);

Note: The parentheses in the previous snippet aren't unique to JSX, and don’t have any effect on your application. They're a signal to you (and your computer) that the multiple lines of code inside are part of the same expression. You could just as well write the header expression like this:

const header = <header>
    <h1>Mozilla Developer Network</h1>
</header>

Of course, your browser can't read JSX without help. When compiled (using a tool like Babel or Parcel), our header expression would look like this:

const header = React.createElement("header", null,
  React.createElement("h1", null, "Mozilla Developer Network")
);

create-react-app takes one argument: the name you'd like to give your app. create-react-app uses this name to make a new directory, then creates the necessary files inside it. Make sure you cd to the place you'd like your app to live on your hard drive, then run the following in your terminal:

npx create-react-app moz-todo-react

The following is a rudimentary example of React usage in HTML with JSX and JavaScript.

<div id="myReactApp"></div>

<script type="text/babel">
  function Greeter(props) {
    return <h1>{props.greeting}</h1>;
  }
  const App = <Greeter greeting="Hello, World!" />;
  ReactDOM.render(App, document.getElementById('myReactApp'));
</script>

When displayed in a web browser the result will be:

<div id="myReactApp">
  <h1>Hello, World!</h1>
</div>

React code is made of entities called components. Components can be rendered to a particular element in the DOM using the React DOM library. When rendering a component, one can pass in values that are known as "props":[8]

ReactDOM.render(<Greeter greeting="Hello World!" />, document.getElementById('myReactApp'));

Function components are declared with a function that then returns some JSX.

const Greeter = (props) => <div>Hello, {props.name}!</div>;

Class-based components are declared using ES6 classes.

class ParentComponent extends React.Component {
  state = { color: 'green' };
  render() {
    return (
      <ChildComponent color={this.state.color} />
    );
  }
}

DevTools should not crawl unmounted subtrees when profiling starts (#…

…23162)

Previously we crawled all subtrees, even not-yet-mounted ones, to initialize context values. This was not only unecessary, but it also caused an error to be thrown. This commit adds a test and fixes that behavior.

We have several examples on the website. Here is the first one to get you started:

function HelloMessage({ name }) {
  return <div>Hello {name}</div>;
}

ReactDOM.render(
  <HelloMessage name="Taylor" />,
  document.getElementById('container')
);