Node.js - klaw
A Node.js file system walker extracted from fs-extra.
Install
npm i --save klaw
Name
klaw
is walk
backwards :p
Usage
klaw(directory, [options])
Returns a Readable stream that iterates
through every file and directory starting with dir
as the root. Every read()
or data
event
returns an object with two properties: path
and stats
. path
is the full path of the file and
stats
is an instance of fs.Stats.
directory
: The directory to recursively walk. Type string
.options
: Readable stream options and
the following:
queueMethod
(string
, default: 'shift'
): Either 'shift'
or 'pop'
. On readdir()
array, call either shift()
or pop()
.pathSorter
(function
, default: undefined
): Sorting function for Arrays.fs
(object
, default: require('fs')
): Use this to hook into the fs
methods or to use mock-fs
Streams 1 (push) example:
var klaw = require('klaw')
var items = []
klaw('/some/dir')
.on('data', function (item) {
items.push(item.path)
})
.on('end', function () {
console.dir(items)
})
Streams 2 & 3 (pull) example:
var klaw = require('klaw')
var items = []
klaw('/some/dir')
.on('readable', function () {
var item
while ((item = this.read())) {
items.push(item.path)
}
})
.on('end', function () {
console.dir(items)
})
If you're not sure of the differences on Node.js streams 1, 2, 3 then I'd
recommend this resource as a good starting point: https://strongloop.com/strongblog/whats-new-io-js-beta-streams3/.
Error Handling
Listen for the error
event.
Example:
var klaw = require('klaw')
klaw('/some/dir')
.on('readable', function () {
var item
while ((item = this.read())) {
}
})
.on('error', function (err, item) {
console.log(err.message)
console.log(item.path)
})
.on('end', function () {
console.dir(items)
})
Aggregation / Filtering / Executing Actions (Through Streams)
On many occasions you may want to filter files based upon size, extension, etc.
Or you may want to aggregate stats on certain file types. Or maybe you want to
perform an action on certain file types.
You should use the module through2
to easily
accomplish this.
Install through2
:
npm i --save through2
Example (skipping directories):
var klaw = require('klaw')
var through2 = require('through2')
var excludeDirFilter = through2.obj(function (item, enc, next) {
if (!item.stats.isDirectory()) this.push(item)
next()
})
var items = []
klaw('/some/dir')
.pipe(excludeDirFilter)
.on('data', function (item) {
items.push(item.path)
})
.on('end', function () {
console.dir(items)
})
Example (totaling size of PNG files):
var klaw = require('klaw')
var path = require('path')
var through2 = require('through2')
var totalPngsInBytes = 0
var aggregatePngSize = through2.obj(function (item, enc, next) {
if (path.extname(item.path) === '.png') {
totalPngsInBytes += item.stats.size
}
this.push(item)
next()
})
klaw('/some/dir')
.pipe(aggregatePngSize)
.on('data', function (item) {
items.push(item.path)
})
.on('end', function () {
console.dir(totalPngsInBytes)
})
Example (deleting all .tmp files):
var fs = require('fs')
var klaw = require('klaw')
var through2 = require('through2')
var deleteAction = through2.obj(function (item, enc, next) {
this.push(item)
if (path.extname(item.path) === '.tmp') {
item.deleted = true
fs.unklink(item.path, next)
} else {
item.deleted = false
next()
}
})
var deletedFiles = []
klaw('/some/dir')
.pipe(deleteAction)
.on('data', function (item) {
if (!item.deleted) return
deletedFiles.push(item.path)
})
.on('end', function () {
console.dir(deletedFiles)
})
You can even chain a bunch of these filters and aggregators together. By using
multiple pipes.
Example (using multiple filters / aggregators):
klaw('/some/dir')
.pipe(filterCertainFiles)
.pipe(deleteSomeOtherFiles)
.on('end', function () {
console.log('all done!')
})
Example passing (piping) through errors:
Node.js does not pipe()
errors. This means that the error on one stream, like
klaw
will not pipe through to the next. If you want to do this, do the following:
var klaw = require('klaw')
var through2 = require('through2')
var excludeDirFilter = through2.obj(function (item, enc, next) {
if (!item.stats.isDirectory()) this.push(item)
next()
})
var items = []
klaw('/some/dir')
.on('error', function (err) { excludeDirFilter.emit('error', err) })
.pipe(excludeDirFilter)
.on('data', function (item) {
items.push(item.path)
})
.on('end', function () {
console.dir(items)
})
Searching Strategy
Pass in options for queueMethod
and pathSorter
to affect how the file system
is recursively iterated. See the code for more details, it's less than 50 lines :)
License
MIT
Copyright (c) 2015 JP Richardson