Using Web3

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Using Web3
This guide walks you through the process of using the Solidity compiler and web3.js to deploy and interact with a Solidity-based smart contract on Harmony. Given Harmony's Ethereum compatibility features, the web3.js library can be used directly with a Harmony node.
Completed code can be found here.​
Installation
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npm i dotenv
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npm i solc
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npm i @truffle/hdwallet-provider web3
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Create a file Counter.sol in root.
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pragma solidity >=0.4.22;
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​
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contract Counter {
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    uint256 private count = 0;
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    uint256 moneyStored = 0;
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​
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    function incrementCounter() public {
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        count += 1;
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    }
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    function decrementCounter() public {
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        count -= 1;
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    }
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​
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    function addMoney() payable public {
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        moneyStored += msg.value;
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    }
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​
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    function getCount() public view returns (uint256) {
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        return count;
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    }
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​
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    function getMoneyStored() public view returns (uint256){
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        return moneyStored;
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    }
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}
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Create compile.js
The only purpose of the compile.js file, is to use the Solidity compiler to output the bytecode and interface of our contract.
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const path = require("path");
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const fs = require("fs");
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const solc = require("solc");
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​
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// Compile contract
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const contractPath = path.resolve(__dirname, "Counter.sol");
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const source = fs.readFileSync(contractPath, "utf8");
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const input = {
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  language: "Solidity",
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  sources: {
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    "Counter.sol": {
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      content: source,
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    },
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  },
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  settings: {
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    outputSelection: {
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      "*": {
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        "*": ["*"],
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      },
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    },
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  },
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};
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const tempFile = JSON.parse(solc.compile(JSON.stringify(input)));
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const contractFile = tempFile.contracts["Counter.sol"]["Counter"];
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module.exports = contractFile;
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​
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Create Deploy.js
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require("dotenv").config();
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const Web3 = require("web3");
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const contractFile = require("./compile");
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const HDWalletProvider = require("@truffle/hdwallet-provider");
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​
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const bytecode = contractFile.evm.bytecode.object;
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const abi = contractFile.abi;
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​
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const provider = new HDWalletProvider(
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  process.env.mneumonic,
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  process.env.rpcEndpoint
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);
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​
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const web3 = new Web3(provider);
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​
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const deploy = async () => {
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  console.log("Deploying....");
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  I;
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  const accounts = await web3.eth.getAccounts();
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  const result = await new web3.eth.Contract(abi)
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    .deploy({ data: "0x" + bytecode })
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    .send({ gas: "3000000", from: accounts[0] });
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​
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  console.log("Contract deployed to", result.options.address);
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  process.exit();
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};
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​
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deploy();
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​
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Finally 
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node deploy.js
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Congratulations
You just deployed your first smart contract on Harmony using web3.js.
Using Hardhat
Using Harmony-JS
Last modified 1yr ago
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Contents
Installation
Congratulations
Installation

Create a file Counter.sol in root.

Create `compile.js`

Create `Deploy.js`

Finally

Congratulations
