【NPM库】- 0x05 - 文件、路径操作

目录
1. importLocal
  1.1. webpack-dev-server 的一个特性 
  1.2. __filename、__dirname
  1.3. path.dirname、path.join、path.resolve、path.relative
  1.4. process.cwd()
  1.5. find-up
  1.6. pkg-dir
  1.7. import-local
2. rimraf
3. glob
  3.1. glob 模式
  3.2. glob 起源
  3.3. glob 示例
4. globby

1. importLocal

1.1. webpack-dev-server 的一个特性

webpack-dev-server 官网描述了其 CLI 的一个特性：

webpack-dev-server will always use a local installation over a global one. https://github.com/webpack/webpack-dev-server

看看效果：

看看 webpack-dev-server 实现：

看看 import-local 实现：

分析一波原理：...

1.2. __filename、__dirname

__filename：当前模块的文件名。这是当前的模块文件的绝对路径。
__dirname：当前模块的目录名。

示例：

1.3. path.dirname、path.join、path.resolve、path.relative

path.dirname(path)
- path.dirname() 方法会返回 path 的目录名。
path.join([...paths])
- The path.join() method joins all given path segments together using the platform-specific separator as a delimiter, then normalizes the resulting path.
- Zero-length path segments are ignored. If the joined path string is a zero-length string then '.' will be returned, representing the current working directory.
path.resolve([...paths])
- The path.resolve() method resolves a sequence of paths or path segments into an absolute path.
path.relative(from, to)
- The path.relative() method returns the relative path from from to to based on the current working directory. If from and to each resolve to the same path (after calling path.resolve() on each), a zero-length string is returned.

示例：

const path = require("path");

console.log(path.dirname(__filename));

const p1 = path.join("/foo", "bar", "baz/asdf", "quuz", "..");
console.log(p1);

const p2 = path.join("./a", "./b");
console.log(p2);

const p3 = path.resolve("/foo/bar", "/tmp/file/");
console.log(p3);

const p4 = path.resolve("wwwroot", "staticfiles/png/", "../gif/image.gif");
console.log(p4);

const p5= path.relative('/data/orandea/test/aaa', '/data/orandea/impl/bbb');
console.log(p5);

1.4. process.cwd()

The process.cwd() method returns the current working directory of the Node.js process.

示例：

1.5. find-up

Find a file or directory by walking up parent directories.

示例：

const findUp = require('find-up');

(async () => {
    console.log(await findUp('unicorn.png'));
    console.log(await findUp(['rainbow.png', 'unicorn.png']));
    console.log(await findUp("unicorn.png", {cwd: __dirname}))
})();

1.6. pkg-dir

Find the root directory of a Node.js project or npm package

源码：

示例：

const pkgDir = require('pkg-dir');

(async () => {
    const dir = await pkgDir(__dirname);
    console.log(dir);
})();

1.7. import-local

Let a globally installed package use a locally installed version of itself if available

示例：

const importLocal = require('import-local');

if (importLocal(__filename)) {
  console.log('Using local version of this package');
} else {
  // Code for both global and local version here…
}

原理：

2. rimraf

rimraf 是 Linux 命令 rm -rf 的 node 版本。就是用来删除目录、删除文件的。

示例：

3. glob

3.1. glob 模式

In computer programming, glob patterns specify sets of filenames with wildcard characters.

mv *.txt textfiles/ moves

moves (mv) all files with names ending in .txt from the current directory to the directory textfiles.

—— 来源于 Wiki

3.2. glob 起源

The command interpreters of the early versions of Unix relied on a separate program to expand wildcard characters in unquoted arguments to a command: /etc/glob. That program performed the expansion and supplied the expanded list of file paths to the command for execution. Its name is an abbreviation for "global command". Later, this functionality was provided as a library function, glob(), used by programs such as the shell.

—— 来源于 Wiki

3.3. glob 示例

4. globby

globby 是 glob 的增强版本

示例：

参考：

import-local： https://github.com/sindresorhus/import-local process.cwd()： https://nodejs.org/api/process.html#process_process_cwd find-up： https://github.com/sindresorhus/find-up resolve-cwd： https://github.com/sindresorhus/resolve-cwd pkg-dir： https://github.com/sindresorhus/pkg-dir