dir-compare

What is dir-compare?

The dir-compare npm package is used to compare the contents of directories. It can compare files and subdirectories, providing detailed information about differences and similarities. This package is useful for tasks such as synchronizing directories, verifying backups, and ensuring consistency between different environments.

What are dir-compare's main functionalities?

Basic Directory Comparison

This feature allows you to compare two directories. The `compareSync` method performs a synchronous comparison, and the `compareContent` option ensures that file contents are compared as well.

const dircompare = require('dir-compare');
const options = { compareContent: true };
const res = dircompare.compareSync('path/to/dir1', 'path/to/dir2', options);
console.log(res);

Asynchronous Directory Comparison

This feature allows you to perform an asynchronous comparison of two directories. The `compare` method returns a promise that resolves with the comparison result.

const dircompare = require('dir-compare');
const options = { compareContent: true };
dircompare.compare('path/to/dir1', 'path/to/dir2', options)
  .then(res => console.log(res))
  .catch(error => console.error(error));

Custom Comparison Options

This feature allows you to customize the comparison process with various options. For example, you can exclude certain file types or include only specific file types in the comparison.

const dircompare = require('dir-compare');
const options = { compareContent: true, excludeFilter: '*.txt', includeFilter: '*.js' };
const res = dircompare.compareSync('path/to/dir1', 'path/to/dir2', options);
console.log(res);

Detailed Comparison Result

This feature provides detailed information about the comparison result. The `diffSet` property contains an array of differences, which you can iterate over to get detailed information about each difference.

const dircompare = require('dir-compare');
const options = { compareContent: true };
const res = dircompare.compareSync('path/to/dir1', 'path/to/dir2', options);
res.diffSet.forEach(dif => console.log(dif));

Other packages similar to dir-compare

diff

The diff package provides a way to compare text differences between two strings or files. While it is more focused on text comparison rather than directory structures, it can be used to compare file contents in a more granular way.

fs-extra

The fs-extra package extends the native Node.js fs module with additional methods, including methods for copying, moving, and removing directories. While it does not provide direct comparison features, it can be used in conjunction with other tools to manage directory contents.

rsyncwrapper

The rsyncwrapper package is a Node.js wrapper for the rsync command-line utility. It can be used to synchronize directories and files between different locations. While it focuses on synchronization rather than comparison, it can be used to achieve similar goals.

README

dir-compare

Node JS directory compare

Starting with v3.0.0 the CLI utility moved to dir-compare-cli.

• Installation
• Library
  • Use
  • Api
  • Glob patterns
  • Symbolic links
  • Handling permission denied errors
• Extension points
  • File content comparators
    • Ignore line endings and white spaces
  • Glob filter
    • Implement .gitignore filter
  • Name comparators
  • Result builder
• UI tools
• Changelog

Installation

npm install dir-compare

Library

Use

const dircompare = require('dir-compare');

const options = { compareSize: true };
// Multiple compare strategy can be used simultaneously - compareSize, compareContent, compareDate, compareSymlink.
// If one comparison fails for a pair of files, they are considered distinct.
const path1 = '...';
const path2 = '...';

// Synchronous
const res = dircompare.compareSync(path1, path2, options)
print(res)

// Asynchronous
dircompare.compare(path1, path2, options)
  .then(res => print(res))
  .catch(error => console.error(error));

function print(result) {
  console.log('Directories are %s', result.same ? 'identical' : 'different')

  console.log('Statistics - equal entries: %s, distinct entries: %s, left only entries: %s, right only entries: %s, differences: %s',
    result.equal, result.distinct, result.left, result.right, result.differences)

  result.diffSet.forEach(dif => console.log('Difference - path: %s, name1: %s, type1: %s, name2: %s, type2: %s, state: %s',
    dif.relativePath, dif.name1, dif.type1, dif.name2, dif.type2, dif.state))
}

Typescript

import { compare, compareSync, Options, Result } from "dir-compare";
const path1 = '...';
const path2 = '...';
const options: Options = { compareSize: true };

const res: Result = compareSync(path1, path2, options);
console.log(res)

compare(path1, path2, options)
  .then(res => console.log(res))
  .catch(error => console.error(error));

Api

compare(path1: string, path2: string, options?: Options): Promise<Result>
compareSync(path1: string, path2: string, options?: Options): Result

More details can be found in the reference documentation:

• compare
• compareSync
• Options
• Result

Common options:

• compareSize
• compareContent
• compareDate
• excludeFilter
• includeFilter
• ignoreCase
• skipSubdirs
• skipEmptyDirs

Glob patterns

Minimatch patterns are used to include/exclude files to be compared.

The pattern is matched against the relative path of the entry being compared.

Following examples assume we are comparing two dir-compare code bases.

const options = { 
  excludeFilter: ".git,node_modules",   //  exclude git and node modules directories  
  excludeFilter: "expected"         ,   //  exclude '/tests/expected' directory  
  excludeFilter: "/tests/expected"  ,   //  exclude '/tests/expected' directory  
  excludeFilter: "**/expected"      ,   //  exclude '/tests/expected' directory  
  excludeFilter: "**/tests/**/*.js" ,   //  exclude all js files in '/tests' directory and subdirectories  

  includeFilter: "*.js,*.yml"       ,   //  include js and yaml files  
  includeFilter: "/tests/**/*.js"   ,   //  include all js files in '/tests' directory and subdirectories  
  includeFilter: "**/tests/**/*.ts"     //  include all js files in '/tests' directory and subdirectories  
}

This behavior can be changed with Glob filter extensions.

Symbolic links

Unless compareSymlink option is used, symbolic links are resolved and any comparison is applied to the file/directory they point to.

Circular loops are handled by breaking the loop as soon as it is detected.

Version 1.x treats broken links as ENOENT: no such file or directory.
Since 2.0 they are treated as a special type of entry - broken-link - and are available as stats (totalBrokenLinks, distinctBrokenLinks, ...).

Using compareSymlink option causes dircompare to check symlink values for equality. In this mode two entries with identical names are considered different if

• one is symlink, the other is not
• both are symlinks but point to different locations

These rules are applied in addition to the other comparison modes; ie. by content, by size...

If entries are different because of symlinks, reason will be different-symlink. Also statistics summarize differences caused by symbolic links.

Handling permission denied errors

Unreadable files or directories are normally reported as errors. The comparison will be interrupted with an EACCES exception. This behavior can be altered with Options.handlePermissionDenied.

Extension points

File content comparators

By default file content is binary compared. As of version 1.5.0 custom file comparison handlers may be specified.

Custom handlers are specified by compareFileSync and compareFileAsync options which correspond to dircompare.compareSync() or dircompare.compare() methods.

A couple of handlers are included in the library:

• binary sync compare - dircompare.fileCompareHandlers.defaultFileCompare.compareSync
• binary async compare - dircompare.fileCompareHandlers.defaultFileCompare.compareAsync
• text sync compare - dircompare.fileCompareHandlers.lineBasedFileCompare.compareSync
• text async compare - dircompare.fileCompareHandlers.lineBasedFileCompare.compareAsync

Use defaultFileCompare as an example to create your own.

Ignore line endings and white spaces

Line based comparator can be used to ignore line ending and white space differences.

const dircompare = require('dir-compare');

const options = {
  compareContent: true,
  compareFileSync: dircompare.fileCompareHandlers.lineBasedFileCompare.compareSync,
  compareFileAsync: dircompare.fileCompareHandlers.lineBasedFileCompare.compareAsync,
  ignoreLineEnding: true,      // Ignore crlf/lf line ending differences
  ignoreWhiteSpaces: true,     // Ignore white spaces at the beginning and end of a line (similar to 'diff -b')
  ignoreAllWhiteSpaces: true,  // Ignore all white space differences (similar to 'diff -w')
  ignoreEmptyLines: true       // Ignores differences caused by empty lines (similar to 'diff -B')
};

const path1 = '...';
const path2 = '...';
const res = dircompare.compareSync(path1, path2, options);
console.log(res)

dircompare.compare(path1, path2, options)
.then(res => console.log(res))

Glob filter

The current implementation of the glob filter uses minimatch and is based on includeFilter and excludeFilter options. While it is meant to fit most use cases, some scenarios are not addressed.

Use filterHandler option to alter this behavior.

The following example demonstrates how to include only files with a specific extension in our comparison.

import { Options, compareSync, Result, FilterHandler, Entry, filterHandlers } from 'dir-compare'
import { extname } from 'path'

var d1 = '...';
var d2 = '...';

const filterByfileExtension: FilterHandler = (entry: Entry, relativePath: string, options: Options): boolean => {
  if (!options.fileExtension) {
    // Fallback on the default 'minimatch' implementation
    return filterHandlers.defaultFilterHandler(entry, relativePath, options)
  }

  return options.fileExtension === extname(entry.name)
}

const options: Options = {
  compareSize: true,
  fileExtension: '.txt',
  filterHandler: filterByfileExtension
}

const res: Result = compareSync(d1, d2, options)

For reference, the default minimatch filter can be found in defaultFilterHandler which is exposed by filterHandlers property.

Implement .gitignore filter

Globby library provides the functionality to parse and apply .gitignore rules. This is a sample implementation that uses globby and dir-compare filter extension.

Usage:

import { Options, compareSync, Result} from 'dir-compare'
import { getGitignoreFilter } from './gitignoreFilter.js'

var d1 = '...';
var d2 = '...';

const options: Options = {
  compareSize: true,
  filterHandler: getGitignoreFilter(d1, d2),
  includeFilter: '*.js'  // if present, regular filters are applied after .gitignore rules.
}

const res: Result = compareSync(d1, d2, options)

Name comparators

If default name comparison is not enough, custom behavior can be specified with compareNameHandler option. Following example adds the possibility to ignore file extensions.

import { Options, compare } from 'dir-compare'
import path from 'path'

const options: Options = {
    compareSize: false,                    // compare only name by disabling size and content criteria
    compareContent: false,
    compareNameHandler: customNameCompare, // new name comparator used to ignore extensions
    ignoreExtension: true,                 // supported by the custom name compare below
};

function customNameCompare(name1: string, name2: string, options: Options) {
    if (options.ignoreCase) {
        name1 = name1.toLowerCase()
        name2 = name2.toLowerCase()
    }
    if (options.ignoreExtension) {
        name1 = path.basename(name1, path.extname(name1))
        name2 = path.basename(name2, path.extname(name2))
    }
    return ((name1 === name2) ? 0 : ((name1 > name2) ? 1 : -1))
}

const path1 = '/tmp/a';
const path2 = '/tmp/b';

const res = compare(path1, path2, options).then(res => {
    console.log(`Same: ${res.same}`)
    if (!res.diffSet) {
        return
    }
    res.diffSet.forEach(dif => console.log(`${dif.name1} ${dif.name2} ${dif.state}`))
})

// Outputs
// icon.svg icon.png equal
// logo.svg logo.jpg equal

For reference, the default name comparator can be found in defaultNameCompare which is exposed by compareNameHandlers property.

Result builder

Result builder is called for each pair of entries encountered during comparison. Its purpose is to append entries in diffSet and eventually update statistics object with new stats.

If needed it can be replaced with custom implementation.

const dircompare = require("dircompare")

const customResultBuilder = function (entry1, entry2, state, level, relativePath, options, statistics, diffSet, reason) {
    ...
}

const options = {
    compareSize: true,
    resultBuilder: customResultBuilder
}
const res = dircompare.compareSync('...', '...', options)

The default builder can be used as an example.

UI tools

• dir-compare-cli
• Visual Studio Code - Compare Folders

Changelog

• v5.0.0 Breaking changes:

  • skipSubdirs option has slightly different behavior. More details in #77

• v4.2.0

  • Updated dependencies
  • Increased test coverage

• v4.1.0

  • Possibility to alter the default Glob filter behavior
  • Ignore files and directories according to .gitignore rules.
  • New origin field in Entry to distinguish between the left or right directory
  • Improved api documentation

• v4.0.0

  • Switched project to typescript
  • Async comparator improvements when comparing large directory structures
    • Heap usage has decreased 3x compared to previous version
    • Works 2x faster when comparing by content
    • Better concurrency. UI apps will be more responsive while comparison is ongoing

  Breaking changes:

  • Using this library to compare two files will ignore the name of the files. More details in #48
  • Removed support for node 8, 9

• v3.3.0 Added skipEmptyDirs option

• v3.2.0 Handle permission denied errors

• v3.1.0 Added ignoreAllWhiteSpaces and ignoreEmptyLines options

• v3.0.0 Moved CLI component into separate project dir-compare-cli

• v2.4.0 New option to customize file/folder name comparison

• v2.3.0 Fixes

• v2.1.0 Removed bluebird dependency

• v2.0.0

  • New option to compare symlinks.
  • New field indicating reason for two entries being distinct.
  • Improved command line output format.
  • Tests are no longer part of published package.
  • Generated Api documentation.

  Breaking changes:

  • Broken links are no longer treated as errors. As a result there are new statistics (leftBrokenLinks, rightBrokenLinks, distinctBrokenLinks, totalBrokenLinks) and new entry type - broken-link. Details in Symbolic links.
  • Typescript correction: new interface Result replaced Statistics.

• v1.8.0

  • globstar patterns
  • typescript corrections
  • removed support for node 0.11, 0.12, iojs

• v1.7.0 performance improvements

• v1.6.0 typescript support

• v1.5.0 added option to ignore line endings and white space differences

• v1.3.0 added date tolerance option

• v1.2.0 added compare by date option

• v1.1.0

  • detect symlink loops
  • improved color scheme for command line utility

• v1.0.0

  • asynchronous comparison
  • new library options: noDiffSet, resultBuilder
  • new statistics: distinctFiles, equalFiles, leftFiles, rightFiles, distinctDirs, equalDirs, leftDirs, rightDirs
  • new --async command line option
  • Fix for https://github.com/tj/commander.js/issues/125

• v0.0.3 Fix file ordering issue for newer node versions