关于使用fs.readdir进行异步目录搜索有什么想法吗?我意识到我们可以引入递归,并调用read目录函数来读取下一个目录,但我有点担心它不是异步的…
什么好主意吗?我已经看了node-walk,它很棒,但它不能像readdir那样只给我数组中的文件。虽然
寻找这样的输出…
['file1.txt', 'file2.txt', 'dir/file3.txt']
关于使用fs.readdir进行异步目录搜索有什么想法吗?我意识到我们可以引入递归,并调用read目录函数来读取下一个目录,但我有点担心它不是异步的…
什么好主意吗?我已经看了node-walk,它很棒,但它不能像readdir那样只给我数组中的文件。虽然
寻找这样的输出…
['file1.txt', 'file2.txt', 'dir/file3.txt']
当前回答
这就是我的答案。希望它能帮助到一些人。
我的重点是使搜索例程可以停在任何地方,对于找到的文件,告诉原始路径的相对深度。
var _fs = require('fs');
var _path = require('path');
var _defer = process.nextTick;
// next() will pop the first element from an array and return it, together with
// the recursive depth and the container array of the element. i.e. If the first
// element is an array, it'll be dug into recursively. But if the first element is
// an empty array, it'll be simply popped and ignored.
// e.g. If the original array is [1,[2],3], next() will return [1,0,[[2],3]], and
// the array becomes [[2],3]. If the array is [[[],[1,2],3],4], next() will return
// [1,2,[2]], and the array becomes [[[2],3],4].
// There is an infinity loop `while(true) {...}`, because I optimized the code to
// make it a non-recursive version.
var next = function(c) {
var a = c;
var n = 0;
while (true) {
if (a.length == 0) return null;
var x = a[0];
if (x.constructor == Array) {
if (x.length > 0) {
a = x;
++n;
} else {
a.shift();
a = c;
n = 0;
}
} else {
a.shift();
return [x, n, a];
}
}
}
// cb is the callback function, it have four arguments:
// 1) an error object if any exception happens;
// 2) a path name, may be a directory or a file;
// 3) a flag, `true` means directory, and `false` means file;
// 4) a zero-based number indicates the depth relative to the original path.
// cb should return a state value to tell whether the searching routine should
// continue: `true` means it should continue; `false` means it should stop here;
// but for a directory, there is a third state `null`, means it should do not
// dig into the directory and continue searching the next file.
var ls = function(path, cb) {
// use `_path.resolve()` to correctly handle '.' and '..'.
var c = [ _path.resolve(path) ];
var f = function() {
var p = next(c);
p && s(p);
};
var s = function(p) {
_fs.stat(p[0], function(err, ss) {
if (err) {
// use `_defer()` to turn a recursive call into a non-recursive call.
cb(err, p[0], null, p[1]) && _defer(f);
} else if (ss.isDirectory()) {
var y = cb(null, p[0], true, p[1]);
if (y) r(p);
else if (y == null) _defer(f);
} else {
cb(null, p[0], false, p[1]) && _defer(f);
}
});
};
var r = function(p) {
_fs.readdir(p[0], function(err, files) {
if (err) {
cb(err, p[0], true, p[1]) && _defer(f);
} else {
// not use `Array.prototype.map()` because we can make each change on site.
for (var i = 0; i < files.length; i++) {
files[i] = _path.join(p[0], files[i]);
}
p[2].unshift(files);
_defer(f);
}
});
}
_defer(f);
};
var printfile = function(err, file, isdir, n) {
if (err) {
console.log('--> ' + ('[' + n + '] ') + file + ': ' + err);
return true;
} else {
console.log('... ' + ('[' + n + '] ') + (isdir ? 'D' : 'F') + ' ' + file);
return true;
}
};
var path = process.argv[2];
ls(path, printfile);
其他回答
使用async/await,这应该工作:
const FS = require('fs');
const readDir = promisify(FS.readdir);
const fileStat = promisify(FS.stat);
async function getFiles(dir) {
let files = await readDir(dir);
let result = files.map(file => {
let path = Path.join(dir,file);
return fileStat(path).then(stat => stat.isDirectory() ? getFiles(path) : path);
});
return flatten(await Promise.all(result));
}
function flatten(arr) {
return Array.prototype.concat(...arr);
}
你可以用蓝鸟。许诺或许诺:
/**
* Returns a function that will wrap the given `nodeFunction`. Instead of taking a callback, the returned function will return a promise whose fate is decided by the callback behavior of the given node function. The node function should conform to node.js convention of accepting a callback as last argument and calling that callback with error as the first argument and success value on the second argument.
*
* @param {Function} nodeFunction
* @returns {Function}
*/
module.exports = function promisify(nodeFunction) {
return function(...args) {
return new Promise((resolve, reject) => {
nodeFunction.call(this, ...args, (err, data) => {
if(err) {
reject(err);
} else {
resolve(data);
}
})
});
};
};
Node 8+内置了Promisify
请参阅我对生成器方法的其他回答,它可以更快地得到结果。
我最近编写了这个代码,并认为在这里分享它是有意义的。代码使用了异步库。
var fs = require('fs');
var async = require('async');
var scan = function(dir, suffix, callback) {
fs.readdir(dir, function(err, files) {
var returnFiles = [];
async.each(files, function(file, next) {
var filePath = dir + '/' + file;
fs.stat(filePath, function(err, stat) {
if (err) {
return next(err);
}
if (stat.isDirectory()) {
scan(filePath, suffix, function(err, results) {
if (err) {
return next(err);
}
returnFiles = returnFiles.concat(results);
next();
})
}
else if (stat.isFile()) {
if (file.indexOf(suffix, file.length - suffix.length) !== -1) {
returnFiles.push(filePath);
}
next();
}
});
}, function(err) {
callback(err, returnFiles);
});
});
};
你可以这样使用它:
scan('/some/dir', '.ext', function(err, files) {
// Do something with files that ends in '.ext'.
console.log(files);
});
我喜欢上面chjj的答案,如果没有那个开始,我就无法创建我的并行循环版本。
var fs = require("fs");
var tree = function(dir, done) {
var results = {
"path": dir
,"children": []
};
fs.readdir(dir, function(err, list) {
if (err) { return done(err); }
var pending = list.length;
if (!pending) { return done(null, results); }
list.forEach(function(file) {
fs.stat(dir + '/' + file, function(err, stat) {
if (stat && stat.isDirectory()) {
tree(dir + '/' + file, function(err, res) {
results.children.push(res);
if (!--pending){ done(null, results); }
});
} else {
results.children.push({"path": dir + "/" + file});
if (!--pending) { done(null, results); }
}
});
});
});
};
module.exports = tree;
我也创建了一个Gist。欢迎评论。我仍然在NodeJS领域起步,所以这是我希望学到更多的一种方式。
独立承诺实现
在这个例子中,我使用的是when.js承诺库。
var fs = require('fs')
, path = require('path')
, when = require('when')
, nodefn = require('when/node/function');
function walk (directory, includeDir) {
var results = [];
return when.map(nodefn.call(fs.readdir, directory), function(file) {
file = path.join(directory, file);
return nodefn.call(fs.stat, file).then(function(stat) {
if (stat.isFile()) { return results.push(file); }
if (includeDir) { results.push(file + path.sep); }
return walk(file, includeDir).then(function(filesInDir) {
results = results.concat(filesInDir);
});
});
}).then(function() {
return results;
});
};
walk(__dirname).then(function(files) {
console.log(files);
}).otherwise(function(error) {
console.error(error.stack || error);
});
我包含了一个可选参数includeDir,如果设置为true,它将在文件列表中包含目录。
qwtel的答案变体,在TypeScript中
import { resolve } from 'path';
import { readdir } from 'fs/promises';
async function* getFiles(dir: string): AsyncGenerator<string> {
const entries = await readdir(dir, { withFileTypes: true });
for (const entry of entries) {
const res = resolve(dir, entry.name);
if (entry.isDirectory()) {
yield* getFiles(res);
} else {
yield res;
}
}
}