在ETH 2.0抵押的一个基本需求是监视其验证者余额，在这个教程中我们将学习如何利用Infura的ETH 2.0 Beacon Chain API编写程序来查询验证者（Validator）的余额。

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离ETH 2.0的零阶段启动越来越近，在witti以及即将上线的altona测试网上参与抵押的兴趣也越来越高涨 —— 调查报告显示超过65%的受访者表示期望抵押其持有的ETH。

首先我们需要引入axio库并创建一个HTTP客户端，从环境变量加载Infura项目ID：

import axios from 'axios';

const instance = axios.create({
  baseURL: 'https://witti.infura.io/',
  auth: {
    username: process.env.INFURA_PROJECT_ID,
    password: '',
  },
});

我们需要定义一些网络相关的参数。前两个有助于我们计算当前周期（epoch），最后一个用来将余额单位从gwei转换为我们更熟悉的eth：

const SECONDS_PER_SLOT = 12;
const SLOTS_PER_EPOCH = 32;
const GWEI_PER_ETH = 1000000000;

接下来我们将查询网络的创世数据用来计算当前周期：

(async () => {
  let response = await instance.get('node/genesis_time')
  const genesisTime = response.data;

  const now = Math.floor(Date.now() / 1000)
  const currentEpoch = Math.floor((now - genesisTime) / (SECONDS_PER_SLOT * SLOTS_PER_EPOCH))

有了这些代码，我们就可以查询验证者（Validator）的当前余额了，这里我们使用写文章时余额最高的验证者的公钥进行查询：

  response = await instance.post('beacon/validators', {
    epoch: currentEpoch.toString(),
    pubkeys: ["0xb0bfa93603f81ecaf3c450b793e71f7372822cd2002534364493e4e497fb5df16d252ae2fdc6bbc0e74d849f918db393"],
  });

  const balanceGwei = response.data[0].balance;
  const balance = balanceGwei / GWEI_PER_ETH;
  
  console.log(`You have ${balance} Ξ2.0`);
})();

当我们运行这个程序时，就可以看到如下输出：

You have 32.500178823 Ξ2.0

下面是查询ETH 2.0验证者余额的完整代码：

import axios from 'axios';

const instance = axios.create({
  baseURL: 'https://witti.infura.io/',
  auth: {
    username: process.env.INFURA_PROJECT_ID,
    password: '',
  },
});

const SECONDS_PER_SLOT = 12;
const SLOTS_PER_EPOCH = 32;
const GWEI_PER_ETH = 1000000000;

(async () => {
  let response = await instance.get('node/genesis_time')
  const genesisTime = response.data;

  const now = Math.floor(Date.now() / 1000)
  const currentEpoch = Math.floor((now - genesisTime) / (SECONDS_PER_SLOT * SLOTS_PER_EPOCH))

  response = await instance.post('beacon/validators', {
    epoch: currentEpoch.toString(),
    pubkeys: ["0xb0bfa93603f81ecaf3c450b793e71f7372822cd2002534364493e4e497fb5df16d252ae2fdc6bbc0e74d849f918db393"],
  });

  const balanceGwei = response.data[0].balance;
  const balance = balanceGwei / GWEI_PER_ETH;
  
  console.log(`You have ${balance} Ξ2.0`);
})();

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原文链接：ETH 2.0验证者余额查询 — 汇智网