Prerequisites

This tutorial takes you step by step from preparing your development environment to understanding the code.

First, confirm that your development environment is configured correctly.

Step 1: Install Node.js and set up the project

1. Install Node.js: Node.js runs JavaScript on the server side. If it isn't on your machine yet, get it from the Node.js website and install it.

2. Create a project directory: In your terminal, go to the location where your project should live and run these commands:

   mkdir chromia-book-review-democd chromia-book-review-demo

3. Initialize a Node.js project: Generate a package.json file with this command:

   npm init -y

Step 2: Install required packages

With the project in place, install the packages it depends on:

npm install typescript postchain-client readline @types/node

• typescript: adds TypeScript support.
• postchain-client: provides the tools you use to communicate with the Chromia blockchain.
• readline: a core Node.js module for reading user input from the command line.

Step 3: Configure TypeScript

TypeScript reads its settings from a file called tsconfig.json. Generate it by running:

npx tsc --init

You get a tsconfig.json file with default settings, which you can adjust to fit your project.

Step 4: Integrate the code

With the packages installed, you can add the code to your project:

1. In your project directory, create a TypeScript file called book_review.ts. Leave it empty for now; you will fill it in over the following sections.

2. Node.js can't run TypeScript directly, so transpile it to JavaScript first:

   npx tsc

   The compiled JavaScript is written to a book_review.js file.

3. Run the result with Node.js:

   node book_review.js

   This runs your code, which interacts with the Chromia blockchain according to what you have written.

Your development environment is now ready: the required packages are installed and TypeScript is integrated into the project. The next section walks through an example client.