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node中的path 模块：用于处理文件和目录的路径的实用工具；经常在一些打包配置中出现

一、path.resolve

• __dirname属于常量，案例中为D:\2024\webpack\webpack-demo\src
• __dirname只能写在最前面，会覆盖之前的所有路径
• / 根目录也会覆盖之前的所有路径，直接变成以他为开始
• path.resolve()相当于path.resolve(__dirname)，__dirname默认都会在第一个位置

// 可以在文件里写入，点击该文件所在文件夹选终端打开，node ./index.js，启动测试代码
console.log("node path", path.resolve());
console.log("node path", path.resolve(__dirname));
console.log("node path", path.resolve(__dirname, ""));
console.log("node path", path.resolve(__dirname, "./"));
console.log("node path", path.resolve(__dirname, "../"));
console.log("node path", path.resolve(__dirname, "/"));
console.log("node path", path.resolve(__dirname, "a", "/b"));
console.log("node path", path.resolve(__dirname, "a", "/b", __dirname));// 结果
node path D:\2024\webpack\webpack-demo\src
node path D:\2024\webpack\webpack-demo\src
node path D:\2024\webpack\webpack-demo\src
node path D:\2024\webpack\webpack-demo\src
node path D:\2024\webpack\webpack-demo
node path D:\
node path D:\b
node path D:\2024\webpack\webpack-demo\src

二、path.join

• 默认调用得到一个点.
• 首位是相对路径就不会有点， 首位是cd …/会保持原样…\，首位是/保持不变\
• 从实际拼接效果上看：a === ./a === /a
• 其他情况为路径拼接，得到一个相对路径值

console.log("node path", path.join());
console.log("node path", path.join("a", "/b"));
console.log("node path", path.join("/a", "/b"));
console.log("node path", path.join("./a", "./b"));
console.log("node path", path.join("../a", "/b"));
console.log("node path", path.join("../a", "../b"));// 结果
node path .
node path a\b
node path \a\b
node path a\b
node path ..\a\b
node path ..\b

• path.join只会帮助拼接，__dirname这种绝对路径常量，如果必要只能一般写第一个，否则会得到奇怪路径；

console.log("node path", path.join(__dirname, "./a", "/b"));
console.log("node path", path.join("./a", __dirname, "/b"));
console.log("node path", path.join("/", __dirname, "/b"));
console.log("node path", path.join("./", __dirname, "/b"));
console.log("node path", path.join(".", __dirname, "/b"));
console.log("node path", path.join("", __dirname, "/b"));// 结果
node path D:\2024\webpack\webpack-demo\src\a\b
node path a\D:\2024\webpack\webpack-demo\src\b
node path \D:\2024\webpack\webpack-demo\src\b
node path D:\2024\webpack\webpack-demo\src\b
node path D:\2024\webpack\webpack-demo\src\b
node path D:\2024\webpack\webpack-demo\src\b