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Comparison of recursive directory listing methods in JavaScript
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/* | |
* Comparison of methods to list all files in a directory | |
* and subdirectories ("recursive directory walk"). | |
* | |
* gunargessner.com 2015-12-25 | |
* | |
*/ | |
var fs = require('fs'); | |
var fsPath = require('path'); | |
var _ = require('highland'); | |
// Synchronous + Imperative Style | |
var walkImperative = function walkImperative(root) { | |
var i, file, dir, results = [], dirs = [root]; | |
while (dirs.length) { | |
var files = fs.readdirSync(dirs[0]); | |
dir = dirs[0]; | |
for (i = 0; i < files.length; i++) { | |
file = fsPath.join(dir, files[i]); | |
if (fs.lstatSync(file).isDirectory()) dirs.push(file); | |
else results.push(file); | |
} | |
dirs.shift(); | |
} | |
return results; | |
}; | |
// Synchronous + Functional style | |
var walkSync = function walkSync(dir) { | |
if (fs.lstatSync(dir).isFile()) { | |
return [dir]; | |
} else { | |
return fs.readdirSync(dir).map(function (file) { | |
file = fsPath.join(dir, file); | |
return walkSync(file); | |
}).reduce(function (pre, cur) { | |
return pre.concat(cur); | |
}, []); | |
} | |
}; | |
// Asynchronous + Callbacks | |
var walkAsync = function walkAsync(dir, cb) { | |
fs.lstat(dir, function (err, stat) { | |
if (stat.isFile()) { | |
cb([dir]); | |
} else { | |
fs.readdir(dir, function (err, files) { | |
var remaining = files.length; | |
var out = []; | |
files.map(function (file) { | |
file = fsPath.join(dir, file); | |
walkAsync(file, function (files) { | |
out = out.concat(files); | |
if (!--remaining) { | |
cb(out); | |
} | |
}); | |
}); | |
}); | |
} | |
}); | |
}; | |
// Asynchronous + Promises | |
function walkPromises(dir) { | |
// fs.lstat from cb-style to promise | |
const lstat = file => | |
new Promise((resolve, reject) => | |
fs.lstat(dir, (err, stat) => { | |
if (err) return reject(err); | |
resolve(stat); | |
}) | |
); | |
// fs.readdir from cb-style to promise | |
const readdir = dir => | |
new Promise((resolve, reject) => | |
fs.readdir(dir, (err, files) => { | |
if (err) return reject(err); | |
resolve(files); | |
}) | |
); | |
return lstat(dir) | |
.then(stat => { | |
if (stat.isFile()) { | |
return [dir]; | |
} else { | |
return readdir(dir) | |
.then(files => | |
Promise.all(files.map(file => { | |
file = fsPath.join(dir, file); | |
return walkPromises(file); | |
})) | |
); | |
} | |
}).then(files => { | |
return files.reduce(function (pre, cur) { | |
return pre.concat(cur); | |
}, []); | |
}); | |
} | |
// Asynchornous + Streams Async-style | |
var walkStreamAsync = function walkStreamAsync(dir) { | |
return _(function (push, next) { | |
fs.lstat(dir, function (err, stat) { | |
if (stat.isFile()) { | |
push(err, dir); | |
push(null, _.nil); | |
} else { | |
fs.readdir(dir, function (err, files) { | |
next(_(files).map(function (file) { | |
file = fsPath.join(dir, file); | |
return walkStreamAsync(file); | |
}).merge()); | |
}); | |
} | |
}); | |
}); | |
}; | |
// Asynchornous + Streams "Stream-style" | |
var walkStream = function walkStream(dir) { | |
return _.wrapCallback(fs.lstat)(dir) | |
.map(function (stat) { | |
if (stat.isFile()) return _([dir]); | |
else { | |
return _.wrapCallback(fs.readdir)(dir).sequence() | |
.map(function (file) { | |
file = fsPath.join(dir, file); | |
return walkStream(file); | |
}).merge(); | |
} | |
}).merge(); | |
}; | |
// Asynchornous + Streams "Stream-style" with fork | |
var walkStreamFork = function walkStreamFork(dir) { | |
var isFile = function (stat) { return stat.isFile(); }; | |
var stat = _.wrapCallback(fs.lstat)(dir); | |
var _dir = stat.observe().reject(isFile).map(function () { | |
return _.wrapCallback(fs.readdir)(dir).sequence() | |
.map(function (file) { | |
file = fsPath.join(dir, file); | |
return walkStreamFork(file); | |
}).merge(); | |
}).merge(); | |
var _file = stat.filter(isFile).map(function () { | |
return dir; | |
}); | |
return _([_file, _dir]).merge(); | |
}; | |
// Example | |
var dir = '.'; | |
var sync = walkSync(dir); | |
var imperative = walkImperative(dir); | |
var async = walkAsync(dir, function (files) {}); | |
var promises = walkPromises(dir).then(function (files) {}); | |
walkStreamAsync(dir).each(function (file) {}); | |
walkStream(dir).each(function (file) {}); | |
walkStreamFork(dir).each(function (file) {}); |
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@mlconnor Thank you! :)
@vqvu This makes sense. Updated now. Thank you!
Also, updated to use ES6 Promises instead of relying on Q library.