ESM import.meta All In One
获取 ES Module 的
meta原数据
import.meta
The import.meta meta-property exposes context-specific metadata to a JavaScript module.
It contains information about the module, such as the module's URL.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/import.meta
使用场景
- 使用
ESM在 Node.js 中实现__dirname功能, 获取模块所在的文件夹的绝对路径 - ...
import fs from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
console.log(`✅ import.meta.url =`, import.meta.url, typeof import.meta.url)
console.log(`✅ __filename =`, __filename, typeof __filename)
console.log(`✅ __dirname`, __dirname, typeof __dirname)
demos
ESM 中实现
__dirname
import fs from 'node:fs';
import path from 'node:path';
import { fileURLToPath } from 'node:url';
// import fs from 'fs';
// import path from 'path';
// import { fileURLToPath } from 'url';
// create one custom `__dirname`, because it doesn't exist in es-module env.
// use `import.meta.url` to get the current module's URL, ✅
// then get the module's folder absolute path
const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
const dir = path.resolve(path.join(__dirname, 'upload');
if (!fs.existsSync(dir)) {
fs.mkdirSync(dir);
}
// OR
if (!fs.existsSync(dir)) {
fs.mkdirSync(dir, {
mode: 0o744, // Not supported on Windows. Default: 0o777
});
}
CJS
__dirname
const fs = require('fs');
const path = require('path');
const dir = path.resolve(path.join(__dirname, 'upload');
if (!fs.existsSync(dir)) {
fs.mkdirSync(dir);
}
// OR
if (!fs.existsSync(dir)) {
fs.mkdirSync(dir, {
mode: 0o744, // Not supported on Windows. Default: 0o777
});
}
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node:fs vs fs
import fs from 'node:fs';
import fs from 'fs';
node:类似https://,file://是一种通信协议 ❓
refs
https://stackoverflow.com/questions/67554506/what-are-the-nodefs-nodepath-etc-modules
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