Parlons des fonctions d'outils courantes dans le module de chemin Node.js

reslove: {
  alias: {
    // __dirname 当前文件所在的目录路径
    'src': path.resolve(__dirname, './src'),
    // process.cwd 当前工作目录
    '@': path.join(process.cwd(), 'src'),
  },
}

module.exports = {
  entry: './path/to/my/entry/file.js',
  output: {
    path: path.resolve(__dirname, 'dist'),
    filename: 'my-first-webpack.bundle.js',
  },
};

let fs = require("fs");
let path = require("path");

// 删除文件夹
let deleDir = (src) => {
    // 读取文件夹
    let children = fs.readdirSync(src);
    children.forEach(item => {
        let childpath = path.join(src, item);
        // 检查文件是否存在
        let file = fs.statSync(childpath).isFile();
        if (file) {
            // 文件存在就删除
            fs.unlinkSync(childpath)
        } else {
            // 继续检测文件夹
            deleDir(childpath)
        }
    })
    // 删除空文件夹
    fs.rmdirSync(src)
}
deleDir("../floor")

resolve(...args) {
  let resolvedDevice = '';
  let resolvedTail = '';
  let resolvedAbsolute = false;

  // 从右到左检测参数
  for (let i = args.length - 1; i >= -1; i--) {
    ......
  }

  // 规范化路径
  resolvedTail = normalizeString(resolvedTail, !resolvedAbsolute, '\\', isPathSeparator);

  return resolvedAbsolute ?
    `${resolvedDevice}\\${resolvedTail}` :
    `${resolvedDevice}${resolvedTail}` || '.';
}

let path;

if (i >= 0) {
  path = args[i];
  // internal/validators
  validateString(path, 'path');
  // path 长度为 0 的话，会直接跳出上述代码块的 for 循环
  if (path.length === 0) {
    continue;
  }
} else if (resolvedDevice.length === 0) {
  // resolvedDevice 的长度为 0，给 path 赋值为当前工作目录
  path = process.cwd();
} else {
  // 赋值为环境对象或者当前工作目录
  path = process.env[`=${resolvedDevice}`] || process.cwd();
  if (path === undefined ||
      (StringPrototypeToLowerCase(StringPrototypeSlice(path, 0, 2)) !==
      StringPrototypeToLowerCase(resolvedDevice) &&
      StringPrototypeCharCodeAt(path, 2) === CHAR_BACKWARD_SLASH)) {
    // 对 path 进行非空与绝对路径判断得出 path 路径
    path = `${resolvedDevice}\\`;
  }
}

const len = path.length;
let rootEnd = 0; // 路径截取结束下标
let device = ''; // 磁盘根 D:\、C:\
let isAbsolute = false; // 是否是磁盘根路径
const code = StringPrototypeCharCodeAt(path, 0);

// path 长度为 1
if (len === 1) {
  // 只有一个路径分隔符 \ 为绝对路径
  if (isPathSeparator(code)) {
    rootEnd = 1;
    isAbsolute = true;
  }
} else if (isPathSeparator(code)) {
  // 可能是 UNC 根，从一个分隔符 \ 开始，至少有一个它就是某种绝对路径（UNC或其他）
  isAbsolute = true;
  // 开始匹配双路径分隔符
  if (isPathSeparator(StringPrototypeCharCodeAt(path, 1))) {
    let j = 2;
    let last = j;
    // 匹配一个或多个非路径分隔符
    while (j < len &&
    !isPathSeparator(StringPrototypeCharCodeAt(path, j))) {
      j++;
    }
    if (j < len && j !== last) {
      const firstPart = StringPrototypeSlice(path, last, j);
      last = j;
      // 匹配一个或多个路径分隔符
      while (j < len &&
              isPathSeparator(StringPrototypeCharCodeAt(path, j))) {
        j++;
      }
      if (j < len && j !== last) {
        last = j;
        while (j < len &&
                !isPathSeparator(StringPrototypeCharCodeAt(path, j))) {
          j++;
        }
        if (j === len || j !== last) {
          device =
            `\\\\${firstPart}\\${StringPrototypeSlice(path, last, j)}`;
          rootEnd = j;
        }
      }
    }
  } else {
    rootEnd = 1;
  }
// 检测磁盘根目录匹配 例：D:，C:\
} else if (isWindowsDeviceRoot(code) && StringPrototypeCharCodeAt(path, 1) === CHAR_COLON) {
  device = StringPrototypeSlice(path, 0, 2);
  rootEnd = 2;
  if (len > 2 && isPathSeparator(StringPrototypeCharCodeAt(path, 2))) {
    isAbsolute = true;
    rootEnd = 3;
  }
}

// 检测磁盘根目录
if (device.length > 0) {
  // resolvedDevice 有值
  if (resolvedDevice.length > 0) {
    if (StringPrototypeToLowerCase(device) !==
        StringPrototypeToLowerCase(resolvedDevice))
      continue;
  } else {
    // resolvedDevice 无值并赋值为磁盘根目录
    resolvedDevice = device;
  }
}

// 绝对路径
if (resolvedAbsolute) {
  // 磁盘根目录存在结束循环
  if (resolvedDevice.length > 0)
    break;
} else {
  // 获取路径前缀进行拼接
  resolvedTail =
    `${StringPrototypeSlice(path, rootEnd)}\\${resolvedTail}`;
  resolvedAbsolute = isAbsolute;
  if (isAbsolute && resolvedDevice.length > 0) {
    // 磁盘根存在便结束循环
    break;
  }
}

if (args.length === 0)
    return '.';

let joined;
let firstPart;
// 从左到右检测参数
for (let i = 0; i < args.length; ++i) {
  const arg = args[i];
  // internal/validators
  validateString(arg, &#39;path&#39;);
  if (arg.length > 0) {
    if (joined === undefined)
      // 把第一个字符串赋值给 joined，并用 firstPart 变量保存第一个字符串以待后面使用
      joined = firstPart = arg;
    else
      // joined 有值，进行 += 拼接操作
      joined += `\\${arg}`;
  }
}

if (joined === undefined)
  return &#39;.&#39;;

let needsReplace = true;
let slashCount = 0;
// 根据 StringPrototypeCharCodeAt 对首个字符串依次进行 code 码提取，并通过 isPathSeparator 方法与定义好的 code 码进行匹配
if (isPathSeparator(StringPrototypeCharCodeAt(firstPart, 0))) {
  ++slashCount;
  const firstLen = firstPart.length;
  if (firstLen > 1 &&
      isPathSeparator(StringPrototypeCharCodeAt(firstPart, 1))) {
    ++slashCount;
    if (firstLen > 2) {
      if (isPathSeparator(StringPrototypeCharCodeAt(firstPart, 2)))
        ++slashCount;
      else {
        needsReplace = false;
      }
    }
  }
}

if (needsReplace) {
  while (slashCount < joined.length &&
          isPathSeparator(StringPrototypeCharCodeAt(joined, slashCount))) {
    slashCount++;
  }

  if (slashCount >= 2)
    joined = `\\${StringPrototypeSlice(joined, slashCount)}`;
}