3. Pages & Routes - Wasp

import useBaseUrl from '@docusaurus/useBaseUrl'; import { ShowForTs } from '@site/src/components/TsJsHelpers';

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

<Tabs groupId="js-ts"> <TabItem value="js" label="JavaScript"> ```wasp title="main.wasp" route RootRoute { path: "/", to: MainPage } page MainPage { // We specify that the React implementation of the page is exported from // `src/MainPage.jsx`. This statement uses standard JS import syntax. // Use `@src` to reference files inside the `src` folder. component: import { MainPage } from "@src/MainPage" } ``` </TabItem> <TabItem value="ts" label="TypeScript"> ```wasp title="main.wasp" route RootRoute { path: "/", to: MainPage } page MainPage { // We specify that the React implementation of the page is exported from // `src/MainPage.tsx`. This statement uses standard JS import syntax. // Use `@src` to reference files inside the `src` folder. component: import { MainPage } from "@src/MainPage" } ``` </TabItem> </Tabs>

Together, these declarations tell Wasp that when a user navigates to /, it should render the named export from src/MainPage.{jsx,tsx}.

The MainPage Component

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

<Tabs groupId="js-ts"> <TabItem value="js" label="JavaScript"> ```jsx title="src/MainPage.jsx" import waspLogo from './waspLogo.png' import './Main.css'

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

</TabItem> <TabItem value="ts" label="TypeScript"> ```tsx title="src/MainPage.tsx" import waspLogo from './waspLogo.png' import './Main.css'

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

</TabItem> </Tabs>

This is a regular functional React component. It also uses the CSS file and a logo image that sit next to it in the src 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:

<Tabs groupId="js-ts"> <TabItem value="js" label="JavaScript"> ```wasp title="main.wasp" route HelloRoute { path: "/hello/:name", to: HelloPage } page HelloPage { component: import { HelloPage } from "@src/HelloPage" } ``` </TabItem> <TabItem value="ts" label="TypeScript"> ```wasp title="main.wasp" route HelloRoute { path: "/hello/:name", to: HelloPage } page HelloPage { component: import { HelloPage } from "@src/HelloPage" } ``` </TabItem> </Tabs>

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

<Tabs groupId="js-ts"> <TabItem value="js" label="JavaScript"> ```jsx title="src/HelloPage.jsx" export const HelloPage = (props) => { return <div>Here's {props.match.params.name}!</div> } ``` </TabItem> <TabItem value="ts" label="TypeScript"> ```tsx title="src/HelloPage.tsx" import { RouteComponentProps } from 'react-router-dom'

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

</TabItem> </Tabs>

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

<ShowForTs> :::tip Type-safe links Since you are using Typescript, you can benefit from using Wasp's type-safe `Link` component and the `routes` object. Check out the [type-safe links docs](../advanced/links) for more details. ::: </ShowForTs>

Cleaning Up

Now that you've seen how Wasp deals with Routes and Pages, it's finally time to build the Todo app.

Start by cleaning up the starter project and removing unnecessary code and files.

First, remove most of the code from the MainPage component:

<Tabs groupId="js-ts"> <TabItem value="js" label="JavaScript"> ```jsx title="src/MainPage.jsx" export const MainPage = () => { return <div>Hello world!</div> } ``` </TabItem> <TabItem value="ts" label="TypeScript"> ```tsx title="src/MainPage.tsx" export const MainPage = () => { return <div>Hello world!</div> } ``` </TabItem> </Tabs>

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

You can now delete redundant files: src/Main.css, src/waspLogo.png, and src/HelloPage.{jsx,tsx} (we won't need this page for the rest of the tutorial).

Since src/HelloPage.{jsx,tsx} no longer exists, remove its route and page declarations from the main.wasp file.

Your Wasp file should now look like this:

<Tabs groupId="js-ts"> <TabItem value="js" label="JavaScript"> ```wasp title="main.wasp" app TodoApp { wasp: { version: "^0.12.0" }, title: "TodoApp" }

route RootRoute { path: "/", to: MainPage }
page MainPage {
  component: import { MainPage } from "@src/MainPage"
}
```

</TabItem> <TabItem value="ts" label="TypeScript"> ```wasp title="main.wasp" app TodoApp { wasp: { version: "^0.12.0" }, title: "TodoApp" }

route RootRoute { path: "/", to: MainPage }
page MainPage {
  component: import { MainPage } from "@src/MainPage"
}
```

</TabItem> </Tabs>

Excellent work!

You now have a basic understanding of Wasp and are ready to start building your TodoApp. We'll implement the app's core features in the following sections.