Simple Start to Smart Contract Development with Hardhat

Welcome to my post about Smart Contract development! This post is mostly just my notes on how to get a super simple smart contract (self executing program on a blockchain) written, deployed and called. For me it is easier to learn something new by doing. When dealing with blockchains and smart contracts however, that "doing" becomes expensive when you are trying to do something many times for educational purposes. Since every write to a blockchain costs something (on Ethereum Virtual Machine, or EVM, based networks, this cost is referred to as a Gas Fee). To avoid the cost of writing to a real blockchain, we'll use a tool called .

In this post we'll create simple contract with the server-side Javascript runtime already installed. Note that my notes below are based on my experience on a Linux server, but it shouldn't be too difficult to adapt to some other OS.

1. Create a directory and node project
   
   mkdir counter-test

cd counter-test/

npm init --yes




2. Add Hardhat to project
   
   npm install --save-dev hardhat






3. Create new Hardhat project
   
   npx hardhat init


   
   



4. 
   

   Now that you have a local blockchain to test with, let's go back to the other terminal and deploy our smart contract with the deploy.js script that we created earlier.
   
   npx hardhat run scripts/deploy.js --network localhost



   
   
   

   If we monitor the Hardhat node we will see our attempt to deploy the smart contract. Note that the From address matches the public address of the first test account. Also make note that we now have a contract address (0x5fbdb2315678afecb367f032d93f642f64180aa3), we'll need this to interact with the contract.

   
   
   
   

Interact With Your Contract From Hardhat Console

Now that our contract is written and deployed on the blockchain, let's try to call some of it's functions.

1. 
   

   Start the Hardhat Javascript console

   
   
   

   npx hardhat console --network localhost

   
   


2. 
   

   We'll store our contract connection in the myContract variable

   
   
   

   const myContract = await ethers.getContractAt("CounterTest","0x5fbdb2315678afecb367f032d93f642f64180aa3")

   
   



3. Next, let's call our getCount() function and see what the current count is:
   
   await myContract.getCount()
   
   You should get "0n" if this is our first run. Ignore the n, this is just indicates the type. You can cast this to an integer or whatever type you need in code if you were using this contract in real-life.




4. Now, let's increment the counter with our incrementCount() function:
   
   await myContract.incrementCount()
   
   You'll see a lot more output from this call since we are actually adding information to the blockchain. Most notably you'll see the blockHash of the transaction and the gasPrice.




5. Call getCount() again to confirm that the counter incremented as expected. The entire interaction should look something like this:
   
   library to interact with your contract.

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