ethers js

1 基本概念

Provider 提供eth链接，对blockchain进行只读操作。

Signer 管理密码，进行数字签字，发送交易。对blockchain进行写操作。

Contract 一个特定合约的blockchain connection。

2 示例代码

1 链接metamask

// A Web3Provider wraps a standard Web3 provider, which is
// what Metamask injects as window.ethereum into each page
const provider = new ethers.providers.Web3Provider(window.ethereum)

// The Metamask plugin also allows signing transactions to
// send ether and pay to change state within the blockchain.
// For this, you need the account signer...
const signer = provider.getSigner()

2 查询

// Look up the current block number
provider.getBlockNumber()
// { Promise: 12261282 }

// Get the balance of an account (by address or ENS name, if supported by network)
balance = await provider.getBalance("ethers.eth")
// { BigNumber: "2337132817842795605" }

// Often you need to format the output to something more user-friendly,
// such as in ether (instead of wei)
ethers.utils.formatEther(balance)
// '2.337132817842795605'

// If a user enters a string in an input field, you may need
// to convert it from ether (as a string) to wei (as a BigNumber)
ethers.utils.parseEther("1.0")
// { BigNumber: "1000000000000000000" }

3 写blockchain

const tx = signer.sendTransaction({
    to: "ricmoo.firefly.eth",
    value: ethers.utils.parseEther("1.0")
});

4 合约

// You can also use an ENS name for the contract address
const daiAddress = "dai.tokens.ethers.eth";

// The ERC-20 Contract ABI, which is a common contract interface
// for tokens (this is the Human-Readable ABI format)
const daiAbi = [
  // Some details about the token
  "function name() view returns (string)",
  "function symbol() view returns (string)",

  // Get the account balance
  "function balanceOf(address) view returns (uint)",

  // Send some of your tokens to someone else
  "function transfer(address to, uint amount)",

  // An event triggered whenever anyone transfers to someone else
  "event Transfer(address indexed from, address indexed to, uint amount)"
];

// The Contract object
const daiContract = new ethers.Contract(daiAddress, daiAbi, provider);

5 监听事件

const daiWithSigner = contract.connect(signer);

// Each DAI has 18 decimal places
const dai = ethers.utils.parseUnits("1.0", 18);

// Send 1 DAI to "ricmoo.firefly.eth"
tx = daiWithSigner.transfer("ricmoo.firefly.eth", dai);

daiContract.on("Transfer", (from, to, amount, event) => {
    console.log(`${ from } sent ${ formatEther(amount) } to ${ to}`);
    // The event object contains the verbatim log data, the
    // EventFragment and functions to fetch the block,
    // transaction and receipt and event functions
});

// A filter for when a specific address receives tokens
myAddress = "0x8ba1f109551bD432803012645Ac136ddd64DBA72";
filter = daiContract.filters.Transfer(null, myAddress)
// {
//   address: 'dai.tokens.ethers.eth',
//   topics: [
//     '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef',
//     null,
//     '0x0000000000000000000000008ba1f109551bd432803012645ac136ddd64dba72'
//   ]
// }

// Receive an event when that filter occurs
daiContract.on(filter, (from, to, amount, event) => {
    // The to will always be "address"
    console.log(`I got ${ formatEther(amount) } from ${ from }.`);
});

5 查询历史事件

// Get the address of the Signer
myAddress = await signer.getAddress()
// '0x8ba1f109551bD432803012645Ac136ddd64DBA72'

// Filter for all token transfers from me
filterFrom = daiContract.filters.Transfer(myAddress, null);
// {
//   address: 'dai.tokens.ethers.eth',
//   topics: [
//     '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef',
//     '0x0000000000000000000000008ba1f109551bd432803012645ac136ddd64dba72'
//   ]
// }

// Filter for all token transfers to me
filterTo = daiContract.filters.Transfer(null, myAddress);
// {
//   address: 'dai.tokens.ethers.eth',
//   topics: [
//     '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef',
//     null,
//     '0x0000000000000000000000008ba1f109551bd432803012645ac136ddd64dba72'
//   ]
// }

// List all transfers sent from me a specific block range
daiContract.queryFilter(filterFrom, 9843470, 9843480)
// { Promise: [
//   {
//     address: '0x6B175474E89094C44Da98b954EedeAC495271d0F',
//     args: [
//       '0x8ba1f109551bD432803012645Ac136ddd64DBA72',
//       '0x8B3765eDA5207fB21690874B722ae276B96260E0',
//       { BigNumber: "4750000000000000000" }
//     ],
//     blockHash: '0x8462eb2fbcef5aa4861266f59ad5f47b9aa6525d767d713920fdbdfb6b0c0b78',
//     blockNumber: 9843476,
//     data: '0x00000000000000000000000000000000000000000000000041eb63d55b1b0000',
//     decode: [Function],
//     event: 'Transfer',
//     eventSignature: 'Transfer(address,address,uint256)',
//     getBlock: [Function],
//     getTransaction: [Function],
//     getTransactionReceipt: [Function],
//     logIndex: 69,
//     removeListener: [Function],
//     removed: false,
//     topics: [
//       '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef',
//       '0x0000000000000000000000008ba1f109551bd432803012645ac136ddd64dba72',
//       '0x0000000000000000000000008b3765eda5207fb21690874b722ae276b96260e0'
//     ],
//     transactionHash: '0x1be23554545030e1ce47391a41098a46ff426382ed740db62d63d7676ff6fcf1',
//     transactionIndex: 81
//   },
//   {
//     address: '0x6B175474E89094C44Da98b954EedeAC495271d0F',
//     args: [
//       '0x8ba1f109551bD432803012645Ac136ddd64DBA72',
//       '0x00De4B13153673BCAE2616b67bf822500d325Fc3',
//       { BigNumber: "250000000000000000" }
//     ],
//     blockHash: '0x8462eb2fbcef5aa4861266f59ad5f47b9aa6525d767d713920fdbdfb6b0c0b78',
//     blockNumber: 9843476,
//     data: '0x00000000000000000000000000000000000000000000000003782dace9d90000',
//     decode: [Function],
//     event: 'Transfer',
//     eventSignature: 'Transfer(address,address,uint256)',
//     getBlock: [Function],
//     getTransaction: [Function],
//     getTransactionReceipt: [Function],
//     logIndex: 70,
//     removeListener: [Function],
//     removed: false,
//     topics: [
//       '0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef',
//       '0x0000000000000000000000008ba1f109551bd432803012645ac136ddd64dba72',
//       '0x00000000000000000000000000de4b13153673bcae2616b67bf822500d325fc3'
//     ],
//     transactionHash: '0x1be23554545030e1ce47391a41098a46ff426382ed740db62d63d7676ff6fcf1',
//     transactionIndex: 81
//   }
// ] }

//
// The following have had the results omitted due to the
// number of entries; but they provide some useful examples
//

// List all transfers sent in the last 10,000 blocks
daiContract.queryFilter(filterFrom, -10000)

// List all transfers ever sent to me
daiContract.queryFilter(filterTo)

Uniswap 常用的方法

provider.estimateGas

Returns an estimate of the amount of gas that would be required to submit transaction to the network.

provider.sendTransaction

Submits transaction to the network to be mined. The transaction must be signed, and be valid (i.e. the nonce is correct and the account has sufficient balance to pay for the transaction).