Tutorial: Using ethers.js and TypeScript to Read a Smart Contract

Prerequisites

Before we begin, make sure you have the following installed on your machine:

1. Node.js (v12.x or higher)
2. npm (comes with Node.js)
3. TypeScript (you can install globally using npm install -g typescript)
4. ethers.js (we will install it during the tutorial)
5. A basic understanding of TypeScript and Solidity

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1. Setting Up the Project

Step 1: Initialize the Project

First, create a new directory for your project and initialize it as a Node.js project:

mkdir hello-world-ethers
cd hello-world-ethers
npm init -y

Step 2: Install Dependencies

You need to install the following dependencies:

• ethers: A library to interact with Ethereum and EVM-compatible blockchains.
• typescript: For TypeScript support.
• ts-node: To run TypeScript files directly.

npm install ethers
npm install --save-dev typescript ts-node

Step 3: Initialize TypeScript

Next, initialize a basic TypeScript configuration:

npx tsc --init

This will generate a tsconfig.json file. You can keep the default configuration.

2. Writing the TypeScript Code

Now, we will write a TypeScript file to interact with the deployed "Hello World!" smart contract.

Step 1: Create the readMessage.ts File

Create a new file named readMessage.ts inside your project directory.

touch readMessage.ts

Step 2: Write the TypeScript Code

Open readMessage.ts and add the following code:

import { ethers } from "ethers";

// Contract details
const contractAddress = "0x757F70Bd8D26F2F2b3F6B623962620e999ABe8B1";
const contractABI = [
  {
    "inputs": [],
    "name": "getMessage",
    "outputs": [
      {
        "internalType": "string",
        "name": "",
        "type": "string"
      }
    ],
    "stateMutability": "view",
    "type": "function"
  }
];

// Connect to the Stability Network
const providerUrl = "https://rpc.testnet.stabilityprotocol.com";
const provider = new ethers.JsonRpcProvider(providerUrl);

async function readMessage() {
  try {
    // Create a contract instance
    const contract = new ethers.Contract(contractAddress, contractABI, provider);
    
    // Call the getMessage function
    const message = await contract.getMessage();
    
    console.log("The current message is:", message);
  } catch (error) {
    console.error("Error reading the message:", error);
  }
}

// Run the function
readMessage();

Explanation:

• Contract Details: We define the contractAddress and the ABI (Application Binary Interface) for the getMessage function. This contract has been deployed by the Stability Team for this example.
• Provider: We connect to the Stability Testnet Network using the JSON RPC provider URL. Ideally, create your own free RPC in Stability Account Manager, as this public RPC will severely limit your reads.
• Contract Interaction: We create a contract instance using ethers.Contract and call the getMessage function to retrieve the message stored on the contract.

3. Running the Code

Step 1: Run the Typescript Code

To run your TypeScript code, use ts-node. This will compile and execute your TypeScript files:

npx ts-node readMessage.ts

Expected Output:

If the everything is set up correctly, you should see something like this in your console:

The current message is: Hello, World!

4. Done!

In this tutorial, you learned how to read a message from a Solidity smart contract using ethers.js and TypeScript on the Stability Network. You can extend this tutorial by interacting with more functions or deploying your own contract!