JavaScript区块链模拟：挖掘难度与时间分析

var difficulty = 5;        // 挖矿难度：哈希值开头所需'0'的数量
var maximumNonce = 50000000; // 最大nonce值，限制挖矿时间
var totalTimes = 300;       // 挖矿总次数

// 注意：由于十六进制值有16种可能，因此每次增加难度级别都会使谜题难度增加16倍。
// 在我的测试中，难度级别为6时，maximumNonce需要远大于500,000,000。

/////////////////////////
// 全局变量设置
/////////////////////////
var pattern = '';
for (var x = 0; x < difficulty; x++) {
  pattern += '0';
}

/////////////////////////
// 函数
/////////////////////////

function sha256(block, chain) {
  // 计算区块内容的SHA256哈希值
  return CryptoJS.SHA256(getText(block, chain));
}

function updateState(block, chain) {
  // 根据区块哈希值设置背景颜色
  if ($('#block' + block + 'chain' + chain + 'hash').val().substr(0, difficulty) === pattern) {
    $('#block' + block + 'chain' + chain + 'well').removeClass('well-error').addClass('well-success');
  }
  else {
    $('#block' + block + 'chain' + chain + 'well').removeClass('well-success').addClass('well-error');
  }
}

function updateHash(block, chain) {
  // 更新区块的SHA256哈希值
  $('#block' + block + 'chain' + chain + 'hash').val(sha256(block, chain));
  updateState(block, chain);
}

function updateChain(block, chain) {
  // 从当前区块开始更新链上的所有区块
  for (var x = block; x <= 5; x++) {
    if (x > 1) {
      $('#block' + x + 'chain' + chain + 'previous').val($('#block' + (x - 1).toString() + 'chain' + chain + 'hash').val());
    }
    updateHash(x, chain);
  }
}

function mine(block, chain, isChain) {
  console.log('开始挖矿!');
  var t0 = performance.now();
  for (var x = 0; x <= maximumNonce; x++) {
    $('#block' + block + 'chain' + chain + 'nonce').val(x);
    $('#block' + block + 'chain' + chain + 'hash').val(sha256(block, chain));
    if ($('#block' + block + 'chain' + chain + 'hash').val().substr(0, difficulty) === pattern) {
      if (isChain) {
        updateChain(block, chain);
      }
      else {
        updateState(block, chain);
      }
      break;
    }
  }
  var t1 = performance.now();
  console.log('挖矿耗时：' + Math.floor(t1 - t0) + ' 毫秒');
}

// 生成数据
for (var i = 1; i <= 1000; i++) {
  $('#block' + i + 'chain1data').val(i);
}

// 挖矿300次并记录每个难度级别的平均时间
var averageTimes = {};
for (var j = 1; j <= difficulty; j++) {
  averageTimes[j] = 0;
}

for (var k = 1; k <= totalTimes; k++) {
  for (var l = 1; l <= difficulty; l++) {
    difficulty = l;
    mine(1, 1, false);
    averageTimes[l] += (performance.now() - t0);
  }
}

for (var m = 1; m <= difficulty; m++) {
  averageTimes[m] /= totalTimes;
  console.log('难度级别 ' + m + ' 的平均挖矿时间：' + averageTimes[m] + ' 毫秒');
}