3. Pages & Routes

In the default main.wasp file created by wasp new, there is a page and a route declaration:

JavaScript

main.wasp

route RootRoute { path: "/", to: MainPage }

page MainPage {
  // We specify that the React implementation of the page is the default export
  // of `src/client/MainPage.jsx`. This statement uses standard JS import syntax.
  // Use `@client` to reference files inside the `src/client` folder.
  component: import Main from "@client/MainPage.jsx"
}

TypeScript

main.wasp

route RootRoute { path: "/", to: MainPage }

page MainPage {
  // We specify that the React implementation of the page is the default export
  // of `src/client/MainPage.tsx`. This statement uses standard JS import syntax.
  // Use `@client` to reference files inside the `src/client` folder.
  component: import Main from "@client/MainPage.tsx"
}

Together, these declarations tell Wasp that when a user navigates to /, it should render the default export from src/client/MainPage.

The MainPage Component

Let's take a look at the React component referenced by the page declaration:

JavaScript

src/client/MainPage.jsx

import waspLogo from './waspLogo.png'
import './Main.css'

const MainPage = () => {
  // ...
}
export default MainPage

TypeScript

src/client/MainPage.tsx

import waspLogo from './waspLogo.png'
import './Main.css'

const MainPage = () => {
  // ...
}
export default MainPage

Since Wasp uses React for the frontend, this is a normal functional React component. It also uses the CSS and logo image that are located next to it in the src/client folder.

That is all the code you need! Wasp takes care of everything else necessary to define, build, and run the web app.

tip

wasp start automatically picks up the changes you make and restarts the app, so keep it running in the background.

Adding a Second Page

To add more pages, you can create another set of page and route declarations. You can even add parameters to the URL path, using the same syntax as React Router. Let's test this out by adding a new page:

JavaScript

main.wasp

route HelloRoute { path: "/hello/:name", to: HelloPage }
page HelloPage {
  component: import Hello from "@client/HelloPage.jsx"
}

TypeScript

main.wasp

route HelloRoute { path: "/hello/:name", to: HelloPage }
page HelloPage {
  component: import Hello from "@client/HelloPage.tsx"
}

When a user visits /hello/their-name, Wasp will render the component exported from src/client/HelloPage and pass the URL parameter the same way as in React Router:

JavaScript

src/client/HelloPage.jsx

const HelloPage = (props) => {
  return <div>Here's {props.match.params.name}!</div>
}

export default HelloPage

TypeScript

src/client/HelloPage.tsx

import { RouteComponentProps } from 'react-router-dom'

const HelloPage = (props: RouteComponentProps<{ name: string }>) => {
  return <div>Here's {props.match.params.name}!</div>
}

export default HelloPage

Now you can visit /hello/johnny and see "Here's johnny!"

Cleaning Up

Let's prepare for building the Todo app by cleaning up the project and removing files and code we won't need. Start by deleting Main.css, waspLogo.png, and HelloPage.tsx that we just created in the src/client/ folder.

Since we deleted HelloPage.tsx, we also need to remember to remove the route and page declarations we wrote for it. Your Wasp file should now look like this:

JavaScript

main.wasp

app TodoApp {
  wasp: {
    version: "^0.11.0"
  },
  title: "Todo app"
}

route RootRoute { path: "/", to: MainPage }
page MainPage {
  component: import Main from "@client/MainPage.jsx"
}

TypeScript

main.wasp

app TodoApp {
  wasp: {
    version: "^0.11.0"
  },
  title: "Todo app"
}

route RootRoute { path: "/", to: MainPage }
page MainPage {
  component: import Main from "@client/MainPage.tsx"
}

Next, we'll remove most of the code from the MainPage component:

JavaScript

src/client/MainPage.jsx

const MainPage = () => {
  return <div>Hello world!</div>
}

export default MainPage

TypeScript

src/client/MainPage.tsx

const MainPage = () => {
  return <div>Hello world!</div>
}

export default MainPage

At this point, the main page should look like this:

In the next section, we'll start implementing some features of the Todo app!