Fs.exist()已弃用。所以我使用fs.stat()来检查目录状态。如果目录不存在，fs.stat()抛出一个错误，并显示类似'没有这样的文件或目录'的消息。然后我创建了一个目录。

const fs = require('fs').promises;

const dir = './dir';
fs.stat(dir).catch(async (err) => {
  if (err.message.includes('no such file or directory')) {
    await fs.mkdir(dir);
  }
});

不，原因有很多。

The path module does not have an exists/existsSync method. It is in the fs module. (Perhaps you just made a typo in your question?) The documentation explicitly discourage you from using exists. fs.exists() is an anachronism and exists only for historical reasons. There should almost never be a reason to use it in your own code. In particular, checking if a file exists before opening it is an anti-pattern that leaves you vulnerable to race conditions: another process may remove the file between the calls to fs.exists() and fs.open(). Just open the file and handle the error when it's not there. Since we're talking about a directory rather than a file, this advice implies you should just unconditionally call mkdir and ignore EEXIST. In general, you should avoid the *Sync methods. They're blocking, which means absolutely nothing else in your program can happen while you go to the disk. This is a very expensive operation, and the time it takes breaks the core assumption of node's event loop. The *Sync methods are usually fine in single-purpose quick scripts (those that do one thing and then exit), but should almost never be used when you're writing a server: your server will be unable to respond to anyone for the entire duration of the I/O requests. If multiple client requests require I/O operations, your server will very quickly grind to a halt. The only time I'd consider using *Sync methods in a server application is in an operation that happens once (and only once), at startup. For example, require actually uses readFileSync to load modules. Even then, you still have to be careful because lots of synchronous I/O can unnecessarily slow down your server's startup time. Instead, you should use the asynchronous I/O methods.

所以如果我们把这些建议放在一起，我们会得到这样的结果:

function ensureExists(path, mask, cb) {
    if (typeof mask == 'function') { // Allow the `mask` parameter to be optional
        cb = mask;
        mask = 0o744;
    }
    fs.mkdir(path, mask, function(err) {
        if (err) {
            if (err.code == 'EEXIST') cb(null); // Ignore the error if the folder already exists
            else cb(err); // Something else went wrong
        } else cb(null); // Successfully created folder
    });
}

我们可以这样使用它:

ensureExists(__dirname + '/upload', 0o744, function(err) {
    if (err) // Handle folder creation error
    else // We're all good
});

当然，这并不能解释边缘情况，比如

如果在程序运行时删除文件夹会发生什么?(假设在启动过程中只检查它是否存在一次) 如果文件夹已经存在，但是权限错误，会发生什么?

对于个人dirs:

var fs = require('fs');
var dir = './tmp';

if (!fs.existsSync(dir)){
    fs.mkdirSync(dir);
}

或者，对于嵌套的dirs:

var fs = require('fs');
var dir = './tmp/but/then/nested';

if (!fs.existsSync(dir)){
    fs.mkdirSync(dir, { recursive: true });
}

适用于v10及以上节点

正如一些回答指出的那样，从节点10开始，您可以对mkdir使用recursive:true

还没有指出的是，当使用recursive:true时，如果目录已经存在，mkdir不会返回错误。

所以你可以这样做:

fsNative.mkdir(dirPath,{recursive:true},(err) => {
    if(err) {
        //note: this does NOT get triggered if the directory already existed
        console.warn(err)
    }
    else{
        //directory now exists 
    }
})

使用承诺

此外，从节点10开始，您可以通过从fs/promises中要求获得所有fs函数的Promise版本

所以把这两件事放在一起，你就得到了这个简单的解决方案:

import * as fs from 'fs/promises';

await fs.mkdir(dirPath, {recursive:true}).catch((err) => {
    //decide what you want to do if this failed
    console.error(err);
});

//directory now exists

使用fs-extra包，你可以用一行代码做到这一点:

const fs = require('fs-extra');

const dir = '/tmp/this/path/does/not/exist';
fs.ensureDirSync(dir);

我发现了一个npm模块，它的工作就像一个魅力。

它只是在需要时递归执行mkdir，如“mkdir -p”。