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// 引入
import { ApiPromise, WsProvider } from '@polkadot/api';

// 創建 api 對象
const wsProvider = new WsProvider('ws://localhost:9944');
const api = await ApiPromise.create({ provider: wsProvider });

// 簡單測試-讀取常量
console.log(api.consts.balances.transactionByteFee.toNumber());

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yarn add @polkadot/keyring

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// 創建 api
// const api = await ...;

api.query.system.events(events => {
  events.forEach(record => {
    // 遍歷所有事件記錄
    const { event, phase } = record;
    const types = event.typeDef;

    // 過濾掉我們不關注的事件

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// 訂閱著該數值
const unsub = await api.query.balances.freeBalance(ADDR, balance => {
  console.log(`balance of ${balance}`);
});

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const unsub = await api.queryMulti([
  // 一個 getter function
  api.query.timestamp.now,
  // 另一個 getter function，及所需參數
  [api.query.balances.freeBalance, ADDR],
  [api.query.system.accountNonce, ADDR],
], ([now, balance, nonce]) => { // 回調函數
  console.log(`${now}: balance of ${balance} and a nonce of ${nonce}`);
});

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// 從 mnemonic 來生成，建議方法：
const PHRASE = 'entire material egg meadow latin bargain dutch coral blood melt acoustic thought';
const newPair = keyring.addFromUri(PHRASE);

// 只限開發時使用，即運行 Substrate 節點時加了 `--dev` 參數：
const alice = keyring.addFromUri('//Alice', { name: 'Alice default' });

// 用 32 位的 16 進制數字生成
const hexPair = keyring.addFromUri('0x1234567890123456789012345678901234567890123456789012345678901234');

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// babe 組件內的常量
console.log(api.consts.babe.epochDuration.toNumber());

// balances 組件內的常量
console.log(api.consts.balances.creationFee.toNumber());
console.log(api.consts.balances.transferFee.toNumber());

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General Instructions

Most workshops at Sub0 will require that you have set up your computer to compile Substrate.

You can use this one-liner to do many of these steps for you automatically:

curl https://getsubstrate.io -sSf | bash -s -- --fast

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use std::str;

fn main() {
  // -- FROM: vec of chars --
  let src1: Vec<char> = vec!['j','{','"','i','m','m','y','"','}'];
  // to String
  let string1: String = src1.iter().collect::<String>();
  // to str
  let str1: &str = &src1.iter().collect::<String>();
  // to vec of byte

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Common OpenSSL Commands with Keys and Certificates

SSL Info

Generate RSA private key with certificate in a single command

openssl req -x509 -newkey rsa:4096 -sha256 -keyout example.key -out example.crt -subj "/CN=example.com" -days 3650 -passout pass:foobar

Generate Certificate Signing Request (CSR) from private key with passphrase

openssl x509 -x509toreq -in example.crt -out example.csr -signkey example.key -passin pass:foobar