375 lines
11 KiB
Plaintext
375 lines
11 KiB
Plaintext
_section: Getting Started @<getting-started>
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_subsection: Installing @<installing>
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Ethers' various Classes and Functions are available to import
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manually from sub-packages under the [@ethersproject](link-ethers-npm)
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organization but for most projects, the umbrella package is the
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easiest way to get started.
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_code: @lang<shell>
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/home/ricmoo> npm install --save ethers
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_subsection: Importing @<importing>
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_heading: Node.js
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_code: node.js require @lang<script>
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const { ethers } = require("ethers");
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_code: ES6 or TypeScript @lang<script>
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import { ethers } from "ethers";
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_heading: Web Browser
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It is generally better practice (for security reasons) to copy the
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[ethers library](link-ethers-js) to your own webserver and serve it
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yourself.
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For quick demos or prototyping though, you can load it in your
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Web Applications from our CDN.
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_code: ES6 in the Browser @lang<html>
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<script type="module">
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import { ethers } from "https://cdn.ethers.io/lib/ethers-5.0.esm.min.js";
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// Your code here...
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</script>
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_code: ES3 (UMD) in the Browser @lang<html>
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<script src="https://cdn.ethers.io/lib/ethers-5.0.umd.min.js"
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type="application/javascript"></script>
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_subsection: Common Terminology @<getting-started--glossary>
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This section needs work...
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_table: Common Terms
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$Provider: A Provider (in ethers) is a class which provides an abstraction
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for a connection to the Ethereum Network. It provides read-only
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access to the Blockchain and its status.
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$Signer: A Signer is a class which (usually) in some way directly or
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indirectly has access to a private key, which can sign messages
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and transactions to authorize the network to charge your account
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ether to perform operations.
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$Contract: A Contract is an abstraction which represents a connection to a
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specific contract on the Ethereum Network, so that applications
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can use it like a normal JavaScript object.
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| **Provider** | $Provider |
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| **Signer** | $Signer |
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| **Contract** | $Contract |
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_subsection: Connecting to Ethereum: Metamask @<getting-started--connecting>
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The quickest and easiest way to experiment and begin developing on
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Ethereum is to use [[link-metamask]], which is a browser extension
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that provides:
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- A connection to the Ethereum network (a [[Provider]])
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- Holds your private key and can sign things (a [[Signer]])
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_code: Connecting to Metamask @lang<script>
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// A Web3Provider wraps a standard Web3 provider, which is
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// what Metamask injects as window.ethereum into each page
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const provider = new ethers.providers.Web3Provider(window.ethereum)
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// The Metamask plugin also allows signing transactions to
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// send ether and pay to change state within the blockchain.
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// For this, you need the account signer...
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const signer = provider.getSigner()
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_subsection: Connecting to Ethereum: RPC @<getting-started--connecting-rpc>
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The [JSON-RPC API](link-jsonrpc) is another popular method for interacting
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with Ethereum and is available in all major Ethereum node implementations
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(e.g. [[link-geth]] and [[link-parity]]) as well as many
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third-party web services (e.g. [[link-infura]]). It typically provides:
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- A connection to the Ethereum network (a [[Provider]])
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- Holds your private key and can sign thing (a [[Signer]])
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_code: Connecting to an RPC client @lang<script>
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// If you don't specify a //url//, Ethers connects to the default
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// (i.e. ``http:/\/localhost:8545``)
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const provider = new ethers.providers.JsonRpcProvider();
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// The provider also allows signing transactions to
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// send ether and pay to change state within the blockchain.
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// For this, we need the account signer...
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const signer = provider.getSigner()
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_heading: Querying the Blockchain @<getting-started--querying>
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Once you have a [[Provider]], you have a read-only connection to the
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blockchain, which you can use to query the current state, fetch historic
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logs, look up deployed code and so on.
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_code: Basic Queries @lang<javascript>
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// Look up the current block number
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provider.getBlockNumber()
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//!
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// Get the balance of an account (by address or ENS name, if supported by network)
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balance = await provider.getBalance("ethers.eth")
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//! async balance
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// Often you need to format the output to something more user-friendly,
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// such as in ether (instead of wei)
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ethers.utils.formatEther(balance)
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//!
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// If a user enters a string in an input field, you may need
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// to convert it from ether (as a string) to wei (as a BigNumber)
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ethers.utils.parseEther("1.0")
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//!
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_heading: Writing to the Blockchain @<getting-started--sending>
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_code: Sending Ether @lang<script>
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// Send 1 ether to an ens name.
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const tx = signer.sendTransaction({
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to: "ricmoo.firefly.eth",
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value: ethers.utils.parseEther("1.0")
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});
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_subsection: Contracts @<getting-started--contracts>
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A Contract is an abstraction of program code which lives on the
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Ethereum blockchain.
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The [[Contract]] object makes it easier to use an on-chain
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Contract as a normal JavaScript object, with the methods
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mapped to encoding and decoding data for you.
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If you are familiar with Databases, this is similar to an //Object Relational Mapper// (ORM).
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In order to communicate with the Contract on-chain, this class
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needs to know what methods are available and how to encode and
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decode the data, which is what the //Application Binary Interface// (ABI)
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provides.
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This class is a //meta-class//, which means its methods are constructed
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at runtime, and when you pass in the ABI to the constructor it uses it
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to determine which methods to add.
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While an on-chain Contract may have many methods available, you can safely ignore
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any methods you don't need or use, providing a smaller subset of the ABI to
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the contract.
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An ABI often comes from the Solidity or Vyper compiler, but you can use the
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Human-Readable ABI in code, which the following examples use.
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_code: Connecting to the DAI Contract @lang<javascript>
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// You can also use an ENS name for the contract address
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const daiAddress = "dai.tokens.ethers.eth";
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// The ERC-20 Contract ABI, which is a common contract interface
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// for tokens (this is the Human-Readable ABI format)
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const daiAbi = [
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// Some details about the token
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"function name() view returns (string)",
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"function symbol() view returns (string)",
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// Get the account balance
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"function balanceOf(address) view returns (uint)",
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// Send some of your tokens to someone else
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"function transfer(address to, uint amount)",
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// An event triggered whenever anyone transfers to someone else
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"event Transfer(address indexed from, address indexed to, uint amount)"
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];
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// The Contract object
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const daiContract = new ethers.Contract(daiAddress, daiAbi, provider);
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_heading: Read-Only Methods @<getting-started--reading>
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_code: Querying the DAI Contract @lang<javascript>
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// <hide>
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const daiAbi = [
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// Some simple details about the token
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"function name() view returns (string)",
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"function symbol() view returns (string)",
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// Get the account balance
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"function balanceOf(address) view returns (uint)",
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];
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const daiContract = new ethers.Contract("dai.tokens.ethers.eth", daiAbi, provider);
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// </hide>
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// Get the ERC-20 token name
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daiContract.name()
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//!
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// Get the ERC-20 token symbol (for tickers and UIs)
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daiContract.symbol()
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//!
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// Get the balance of an address
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balance = await daiContract.balanceOf("ricmoo.firefly.eth")
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//! async balance
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// Format the DAI for displaying to the user
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ethers.utils.formatUnits(balance, 18)
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//!
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_heading: State Changing Methods @<getting-started--writing>
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_code: Sending DAI @lang<script>
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// The DAI Contract is currently connected to the Provider,
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// which is read-only. You need to connect to a Signer, so
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// that you can pay to send state-changing transactions.
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const daiWithSigner = contract.connect(signer);
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// Each DAI has 18 decimal places
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const dai = ethers.utils.parseUnits("1.0", 18);
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// Send 1 DAI to "ricmoo.firefly.eth"
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tx = daiWithSigner.transfer("ricmoo.firefly.eth", dai);
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_heading: Listening to Events @<getting-started--events>
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_code: Listening to Events @lang<javascript>
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// <hide>
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const daiAbi = [
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"event Transfer(address indexed, address indexed, uint256)"
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];
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const daiContract = new ethers.Contract("dai.tokens.ethers.eth", daiAbi, provider);
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const formatEther = ethers.utils.formatEther;
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// </hide>
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// Receive an event when ANY transfer occurs
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daiContract.on("Transfer", (from, to, amount, event) => {
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console.log(`${ from } sent ${ formatEther(amount) } to ${ to}`);
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// The event object contains the verbatim log data, the
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// EventFragment and functions to fetch the block,
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// transaction and receipt and event functions
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});
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// A filter for when a specific address receives tokens
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myAddress = "0x8ba1f109551bD432803012645Ac136ddd64DBA72";
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filter = daiContract.filters.Transfer(null, myAddress)
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// <hide>
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filter
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// </hide>
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//!
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// Receive an event when that filter occurs
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daiContract.on(filter, (from, to, amount, event) => {
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// The to will always be "address"
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console.log(`I got ${ formatEther(amount) } from ${ from }.`);
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});
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// <hide>
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// Don't want to block the docs from compiling...
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daiContract.removeAllListeners();
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// </hide>
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_heading: Query Historic Events @<getting-started--history>
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_code: Filtering Historic Events @lang<javascript>
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// <hide>
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const signer = new ethers.VoidSigner("0x8ba1f109551bD432803012645Ac136ddd64DBA72");
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const daiAbi = [
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"event Transfer(address indexed, address indexed, uint256)"
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];
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const daiContract = new ethers.Contract("dai.tokens.ethers.eth", daiAbi, provider);
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//!
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// </hide>
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// Get the address of the Signer
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myAddress = await signer.getAddress()
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//! async myAddress
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// Filter for all token transfers from me
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filterFrom = daiContract.filters.Transfer(myAddress, null);
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// <hide>
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filterFrom
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// </hide>
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//!
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// Filter for all token transfers to me
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filterTo = daiContract.filters.Transfer(null, myAddress);
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// <hide>
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filterTo
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// </hide>
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//!
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// List all transfers sent from me a specific block range
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daiContract.queryFilter(filterFrom, 9843470, 9843480)
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//!
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//
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// The following have had the results omitted due to the
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// number of entries; but they provide some useful examples
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//
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// List all transfers sent in the last 10,000 blocks
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daiContract.queryFilter(filterFrom, -10000)
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// List all transfers ever sent to me
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daiContract.queryFilter(filterTo)
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_subsection: Signing Messages @<getting-started--signing>
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_code: Signing Messages @lang<javascript>
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// <hide>
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const signer = ethers.Wallet.createRandom();
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//!
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// </hide>
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// To sign a simple string, which are used for
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// logging into a service, such as CryptoKitties,
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// pass the string in.
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signature = await signer.signMessage("Hello World");
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//! async signature
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//
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// A common case is also signing a hash, which is 32
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// bytes. It is important to note, that to sign binary
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// data it MUST be an Array (or TypedArray)
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//
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// This string is 66 characters long
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message = "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"
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// This array representation is 32 bytes long
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messageBytes = ethers.utils.arrayify(message);
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//!
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// To sign a hash, you most often want to sign the bytes
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signature = await signer.signMessage(messageBytes)
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//! async signature
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