Creating new project

Run the following command in your terminal to create a new Wasp project:

$ wasp new TodoApp

Enter the created directory and run:

$ cd TodoApp$ wasp start

You have just ran your app in the development mode!

note

wasp start might take a little bit longer, due to the first time setup.

You will be seeing a lot of different output from client, server and database setting themselves up. Once ready, a new tab should open in your browser at http://localhost:3000, with simple placeholder page:

We just set the foundations of our app! We don't have yet the features to show it, but Wasp already generated for us full front-end and back-end code of the app. Take a peek at TodoApp/.wasp/out if you are curious and see how it looks like!

Taking a closer look at the code

Let's inspect Wasp project that we just created:

TodoApp/├── main.wasp # Here goes our Wasp code.├── ext/      # Here goes our (external) JS/CSS/HTML/... code.│   └── MainPage.js│   └── Main.css│   └── waspLogo.png├── .gitignore└── .wasproot

Let's start with main.wasp file which introduces 3 new concepts: app, page and route.

main.wasp

app TodoApp { // Main declaration, defines a new web app.  title: "TodoApp" // Used as a browser tab title.}
route "/" -> page Main // Render page Main on url `/` (default url).
page Main {  // We specify that ReactJS implementation of our page can be  // found in `ext/MainPage.js` as a default export (uses standard  // js import syntax).  component: import Main from "@ext/MainPage.js"}

And now to that React component we referenced in the page Main { ... } declaration in main.wasp:

ext/MainPage.js

import React from 'react'import waspLogo from './waspLogo.png'import './Main.css'
const MainPage = () => {  ...}export default MainPage

As we can see, this is just a simple functional React component using css and wasp logo that are next to it.

This is all the code! Wasp in the background takes care of everything else needed to define, build and run a web app.

tip

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

Cleaning up

Let's make our first changes! To prepare the clean slate for building the TodoApp, delete all the files from ext/ dir except for MainPage.js, and let's also make MainPage component much simpler:

ext/MainPage.js

import React from 'react'
const MainPage = () => {  return <div> Hello world! </div>}export default MainPage

At this point, you should be seeing smth like

Ok, next step, some real Todo app features!