Ethers.js
Ethers.js JavaScript Library
Introduction
The Ethers.js library provides a set of tools to interact with Ethereum Nodes with JavaScript, similar to Web3.js. Phron has an Ethereum-like API available that is fully compatible with Ethereum-style JSON-RPC invocations. Therefore, developers can leverage this compatibility and use the Ethers.js library to interact with a Phron node as if they were doing so on Ethereum. For more information on Ethers.js, check their documentation site.
In this guide, you'll learn how to use the Ethers.js library to send a transaction and deploy a contract on Phron.
Checking Prerequisites
For the examples in this guide, you will need to have the following:
An account with funds. You can get DEV tokens for testing on Phron once every 24 hours from the Phron Faucet
To test out the examples in this guide on Phron, you will need to have your own endpoint and API key, which you can get from one of the supported Endpoint Providers
NoteThe examples in this guide assume you have a MacOS or Ubuntu 22.04-based environment and will need to be adapted accordingly for Windows.
Installing Ethers.js
To get started, you'll need to start a basic JavaScript project. First, create a directory to store all of the files you'll be creating throughout this guide and initialize the project with the following command:
For this guide, you'll need to install the Ethers.js library and the Solidity compiler. To install both NPM packages, you can run the following command:
Setting up the Ethers Provider
Throughout this guide, you'll be creating a bunch of scripts that provide different functionality such as sending a transaction, deploying a contract, and interacting with a deployed contract. In most of these scripts you'll need to create an Ethers provider to interact with the network.
To configure your project for Phron, you will need to have your own endpoint and API key, which you can get from one of the supported Endpoint Providers.
To create a provider, you can take the following steps:
Import the
ethers
libraryDefine the
providerRPC
object, which can include the network configurations for any of the networks you want to send a transaction on. You'll include thename
,rpc
, andchainId
for each networkCreate the
provider
using theethers.JsonRpcProvider
method
Save this code snippet as you'll need it for the scripts that are used in the following sections.
Send a Transaction
During this section, you'll be creating a couple of scripts. The first one will be to check the balances of your accounts before trying to send a transaction. The second script will actually send the transaction.
You can also use the balance script to check the account balances after the transaction has been sent.
Check Balances Script
You'll only need one file to check the balances of both addresses before and after the transaction is sent. To get started, you can create a balances.js
file by running:
Next, you will create the script for this file and complete the following steps:
Set up the Ethers provider
Define the
addressFrom
andaddressTo
variablesCreate the asynchronous
balances
function which wraps theprovider.getBalance
methodUse the
provider.getBalance
function to fetch the balances for theaddressFrom
andaddressTo
addresses. You can also leverage theethers.formatEther
function to transform the balance into a more readable number in ETHLastly, run the
balances
function
To run the script and fetch the account balances, you can run the following command:
If successful, the balances for the origin and receiving address will be displayed in your terminal in DEV.
Send Transaction Script
You'll only need one file for executing a transaction between accounts. For this example, you'll be transferring 1 DEV token from an origin address (from which you hold the private key) to another address. To get started, you can create a transaction.js
file by running:
Next, you will create the script for this file and complete the following steps:
Set up the Ethers provider
Define the
privateKey
and theaddressTo
variables. The private key is required to create a wallet instance. Note: This is for example purposes only. Never store your private keys in a JavaScript fileCreate a wallet using the
privateKey
andprovider
from the previous steps. The wallet instance is used to sign transactionsCreate the asynchronous
send
function which wraps the transaction object and thewallet.sendTransaction
methodCreate the transaction object which only requires the recipient's address and the amount to send. Note that
ethers.parseEther
can be used, which handles the necessary unit conversions from Ether to Wei - similar to usingethers.parseUnits(value, 'ether')
Send the transaction using the
wallet.sendTransaction
method and then useawait
to wait until the transaction is processed and the transaction receipt is returnedLastly, run the
send
function
To run the script, you can run the following command in your terminal:
If the transaction was succesful, in your terminal you'll see the transaction hash has been printed out.
You can also use the balances.js
script to check that the balances for the origin and receiving accounts have changed. The entire workflow would look like this:
Deploy a Contract
The contract you'll be compiling and deploying in the next couple of sections is a simple incrementer contract, arbitrarily named Incrementer.sol
. You can get started by creating a file for the contract:
Next, you can add the Solidity code to the file:
The constructor
function, which runs when the contract is deployed, sets the initial value of the number variable stored on-chain (the default is 0
). The increment
function adds the _value
provided to the current number, but a transaction needs to be sent, which modifies the stored data. Lastly, the reset
function resets the stored value to zero.
NoteThis contract is a simple example for illustration purposes only and does not handle values wrapping around.
Compile Contract Script
In this section, you'll create a script that uses the Solidity compiler to output the bytecode and interface (ABI) for the Incrementer.sol
contract. To get started, you can create a compile.js
file by running:
Next, you will create the script for this file and complete the following steps:
Import the
fs
andsolc
packagesUsing the
fs.readFileSync
function, you'll read and save the file contents ofIncrementer.sol
tosource
Build the
input
object for the Solidity compiler by specifying thelanguage
,sources
, andsettings
to be usedUsing the
input
object, you can compile the contract usingsolc.compile
Extract the compiled contract file and export it to be used in the deployment script
Deploy Contract Script
With the script for compiling the Incrementer.sol
contract in place, you can then use the results to send a signed transaction that deploys it. To do so, you can create a file for the deployment script called deploy.js
:
Next, you will create the script for this file and complete the following steps:
Import the contract file from
compile.js
Set up the Ethers provider
Define the
privateKey
for the origin account. The private key is required to create a wallet instance. Note: This is for example purposes only. Never store your private keys in a JavaScript fileCreate a wallet using the
privateKey
andprovider
from the previous steps. The wallet instance is used to sign transactionsLoad the contract
bytecode
andabi
for the compiled contractCreate a contract instance with signer using the
ethers.ContractFactory
function, providing theabi
,bytecode
, andwallet
as parametersCreate the asynchronous
deploy
function that will be used to deploy the contractWithin the
deploy
function, use theincrementer
contract instance to calldeploy
and pass in the initial value. For this example, you can set the initial value to5
. This will send the transaction for contract deployment. To wait for a transaction receipt you can use thedeployed
method of the contract deployment transactionLastly, run the
deploy
function
To run the script, you can enter the following command into your terminal:
If successful, the contract's address will be displayed in the terminal.
Read Contract Data (Call Methods)
Call methods are the type of interaction that don't modify the contract's storage (change variables), meaning no transaction needs to be sent. They simply read various storage variables of the deployed contract.
To get started, you can create a file and name it get.js
:
Then you can take the following steps to create the script:
Import the
abi
from thecompile.js
fileSet up the Ethers provider
Create the
contractAddress
variable using the address of the deployed contractCreate an instance of the contract using the
ethers.Contract
function and passing in thecontractAddress
,abi
, andprovider
Create the asynchronous
get
functionUse the contract instance to call one of the contract's methods and pass in any inputs if necessary. For this example, you will call the
number
method which doesn't require any inputs. You can useawait
which will return the value requested once the request promise resolvesLastly, call the
get
function
To run the script, you can enter the following command in your terminal:
If successful, the value will be displayed in the terminal.
Interact with Contract (Send Methods)
Send methods are the type of interaction that modify the contract's storage (change variables), meaning a transaction needs to be signed and sent. In this section, you'll create two scripts: one to increment and one to reset the incrementer. To get started, you can create a file for each script and name them increment.js
and reset.js
:
Open the increment.js
file and take the following steps to create the script:
Import the
abi
from thecompile.js
fileSet up the Ethers provider
Define the
privateKey
for the origin account, thecontractAddress
of the deployed contract, and the_value
to increment by. The private key is required to create a wallet instance. Note: This is for example purposes only. Never store your private keys in a JavaScript fileCreate a wallet using the
privateKey
andprovider
from the previous steps. The wallet instance is used to sign transactionsCreate an instance of the contract using the
ethers.Contract
function and passing in thecontractAddress
,abi
, andprovider
Create the asynchronous
increment
functionUse the contract instance to call one of the contract's methods and pass in any inputs if necessary. For this example, you will call the
increment
method which requires the value to increment by as an input. You can useawait
which will return the value requested once the request promise resolvesLastly, call the
increment
function
To run the script, you can enter the following command in your terminal:
If successful, the transaction hash will be displayed in the terminal. You can use the get.js
script alongside the increment.js
script to make sure that value is changing as expected:
Next you can open the reset.js
file and take the following steps to create the script:
Import the
abi
from thecompile.js
fileSet up the Ethers provider
Define the
privateKey
for the origin account and thecontractAddress
of the deployed contract. The private key is required to create a wallet instance. Note: This is for example purposes only. Never store your private keys in a JavaScript fileCreate a wallet using the
privateKey
andprovider
from the previous steps. The wallet instance is used to sign transactionsCreate an instance of the contract using the
ethers.Contract
function and passing in thecontractAddress
,abi
, andprovider
Create the asynchronous
reset
functionUse the contract instance to call one of the contract's methods and pass in any inputs if necessary. For this example, you will call the
reset
method which doesn't require any inputs. You can useawait
which will return the value requested once the request promise resolvesLastly, call the
reset
function
To run the script, you can enter the following command in your terminal:
If successful, the transaction hash will be displayed in the terminal. You can use the get.js
script alongside the reset.js
script to make sure that value is changing as expected:
This tutorial is for educational purposes only. As such, any contracts or code created in this tutorial should not be used in production.The information presented herein has been provided by third parties and is made available solely for general information purposes. Phron does not endorse any project listed and described on the Phron Doc Website (https://docs.Phron.ai/). Phron does not warrant the accuracy, completeness or usefulness of this information. Any reliance you place on such information is strictly at your own risk. Phron disclaims all liability and responsibility arising from any reliance placed on this information by you or by anyone who may be informed of any of its contents. All statements and/or opinions expressed in these materials are solely the responsibility of the person or entity providing those materials and do not necessarily represent the opinion of Phron. The information should not be construed as professional or financial advice of any kind. Advice from a suitably qualified professional should always be sought in relation to any particular matter or circumstance. The information herein may link to or integrate with other websites operated or content provided by third parties, and such other websites may link to this website. Phron has no control over any such other websites or their content and will have no liability arising out of or related to such websites or their content. The existence of any such link does not constitute an endorsement of such websites, the content of the websites, or the operators of the websites. These links are being provided to you only as a convenience and you release and hold Phron harmless from any and all liability arising from your use of this information or the information provided by any third-party website or service.
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