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
为了以防有人发现它有用,我还整理了一个同步版本。
var walk = function(dir) {
var results = [];
var list = fs.readdirSync(dir);
list.forEach(function(file) {
file = dir + '/' + file;
var stat = fs.statSync(file);
if (stat && stat.isDirectory()) {
/* Recurse into a subdirectory */
results = results.concat(walk(file));
} else {
/* Is a file */
results.push(file);
}
});
return results;
}
提示:在筛选时使用更少的资源。这个函数本身的过滤器。例如:替换results.push(文件);下面的代码。根据需要调整:
file_type = file.split(".").pop();
file_name = file.split(/(\\|\/)/g).pop();
if (file_type == "json") results.push(file);
其他回答
为了以防有人发现它有用,我还整理了一个同步版本。
var walk = function(dir) {
var results = [];
var list = fs.readdirSync(dir);
list.forEach(function(file) {
file = dir + '/' + file;
var stat = fs.statSync(file);
if (stat && stat.isDirectory()) {
/* Recurse into a subdirectory */
results = results.concat(walk(file));
} else {
/* Is a file */
results.push(file);
}
});
return results;
}
提示:在筛选时使用更少的资源。这个函数本身的过滤器。例如:替换results.push(文件);下面的代码。根据需要调整:
file_type = file.split(".").pop();
file_name = file.split(/(\\|\/)/g).pop();
if (file_type == "json") results.push(file);
异步
const fs = require('fs')
const path = require('path')
const readdir = (p, done, a = [], i = 0) => fs.readdir(p, (e, d = []) =>
d.map(f => readdir(a[a.push(path.join(p, f)) - 1], () =>
++i == d.length && done(a), a)).length || done(a))
readdir(__dirname, console.log)
Sync
const fs = require('fs')
const path = require('path')
const readdirSync = (p, a = []) => {
if (fs.statSync(p).isDirectory())
fs.readdirSync(p).map(f => readdirSync(a[a.push(path.join(p, f)) - 1], a))
return a
}
console.log(readdirSync(__dirname))
异步读
function readdir (currentPath, done, allFiles = [], i = 0) {
fs.readdir(currentPath, function (e, directoryFiles = []) {
if (!directoryFiles.length)
return done(allFiles)
directoryFiles.map(function (file) {
var joinedPath = path.join(currentPath, file)
allFiles.push(joinedPath)
readdir(joinedPath, function () {
i = i + 1
if (i == directoryFiles.length)
done(allFiles)}
, allFiles)
})
})
}
readdir(__dirname, console.log)
注意:两个版本都将跟随符号链接(与原始fs.readdir相同)
There are basically two ways of accomplishing this. In an async environment you'll notice that there are two kinds of loops: serial and parallel. A serial loop waits for one iteration to complete before it moves onto the next iteration - this guarantees that every iteration of the loop completes in order. In a parallel loop, all the iterations are started at the same time, and one may complete before another, however, it is much faster than a serial loop. So in this case, it's probably better to use a parallel loop because it doesn't matter what order the walk completes in, just as long as it completes and returns the results (unless you want them in order).
一个平行循环看起来是这样的:
var fs = require('fs');
var path = require('path');
var walk = function(dir, done) {
var results = [];
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) {
file = path.resolve(dir, file);
fs.stat(file, function(err, stat) {
if (stat && stat.isDirectory()) {
walk(file, function(err, res) {
results = results.concat(res);
if (!--pending) done(null, results);
});
} else {
results.push(file);
if (!--pending) done(null, results);
}
});
});
});
};
一个串行循环看起来像这样:
var fs = require('fs');
var path = require('path');
var walk = function(dir, done) {
var results = [];
fs.readdir(dir, function(err, list) {
if (err) return done(err);
var i = 0;
(function next() {
var file = list[i++];
if (!file) return done(null, results);
file = path.resolve(dir, file);
fs.stat(file, function(err, stat) {
if (stat && stat.isDirectory()) {
walk(file, function(err, res) {
results = results.concat(res);
next();
});
} else {
results.push(file);
next();
}
});
})();
});
};
并且在你的主目录中测试它(警告:如果你的主目录中有很多东西,结果列表将会非常大):
walk(process.env.HOME, function(err, results) {
if (err) throw err;
console.log(results);
});
编辑:改进的示例。
使用承诺(Q)以函数式风格解决此问题:
var fs = require('fs'),
fsPath = require('path'),
Q = require('q');
var walk = function (dir) {
return Q.ninvoke(fs, 'readdir', dir).then(function (files) {
return Q.all(files.map(function (file) {
file = fsPath.join(dir, file);
return Q.ninvoke(fs, 'lstat', file).then(function (stat) {
if (stat.isDirectory()) {
return walk(file);
} else {
return [file];
}
});
}));
}).then(function (files) {
return files.reduce(function (pre, cur) {
return pre.concat(cur);
});
});
};
它返回一个数组的promise,所以你可以这样使用它:
walk('/home/mypath').then(function (files) { console.log(files); });
它使用了节点8中最多的新功能,包括Promises、util/promisify、destructuring、async-await、map+reduce等等,让你的同事在试图弄清楚发生了什么时挠头。
节点 8+
没有外部依赖。
const { promisify } = require('util');
const { resolve } = require('path');
const fs = require('fs');
const readdir = promisify(fs.readdir);
const stat = promisify(fs.stat);
async function getFiles(dir) {
const subdirs = await readdir(dir);
const files = await Promise.all(subdirs.map(async (subdir) => {
const res = resolve(dir, subdir);
return (await stat(res)).isDirectory() ? getFiles(res) : res;
}));
return files.reduce((a, f) => a.concat(f), []);
}
使用
getFiles(__dirname)
.then(files => console.log(files))
.catch(e => console.error(e));
节点 10.10+
更新到节点10+,甚至更多的whizbang:
const { resolve } = require('path');
const { readdir } = require('fs').promises;
async function getFiles(dir) {
const dirents = await readdir(dir, { withFileTypes: true });
const files = await Promise.all(dirents.map((dirent) => {
const res = resolve(dir, dirent.name);
return dirent.isDirectory() ? getFiles(res) : res;
}));
return Array.prototype.concat(...files);
}
请注意,从节点11.15.0开始,您可以使用files.flat()而不是array. prototype.concat(…files)来扁平化files数组。
11 +节点
如果你想让所有人都大吃一惊,你可以使用下面使用异步迭代器的版本。除了非常酷之外,它还允许使用者每次提取一个结果,这使得它更适合于真正大的目录。
const { resolve } = require('path');
const { readdir } = require('fs').promises;
async function* getFiles(dir) {
const dirents = await readdir(dir, { withFileTypes: true });
for (const dirent of dirents) {
const res = resolve(dir, dirent.name);
if (dirent.isDirectory()) {
yield* getFiles(res);
} else {
yield res;
}
}
}
用法发生了变化,因为返回类型现在是异步迭代器而不是promise
;(async () => {
for await (const f of getFiles('.')) {
console.log(f);
}
})()
如果有人感兴趣,我在这里写了更多关于异步迭代器的文章:https://qwtel.com/posts/software/async-generators-in-the-wild/