mergefs

Like Object.assign but recursive and for files.

The Idea

Specify an output folder, and any number of input folders. They will be merged in order to the output, overwriting files duplicated by name.

In addition, you can also list specific filepaths, in which case only those files will be merged from the input folders and written to the output folders.

The Library

You can import or require or whatnot the usual ways:

const mergefs = require('mergefs')
// or
import { mergefs } from 'mergefs'

Then you call that function, specifying a single output path and an ordered array of input paths, with an optional list of file paths:

await mergefs({
    // required
    output: './out',
    // required
    input: [
        './foo',
        './bar',
        './bizz'
    ],
    // optional
    files: [
        'fizz/buzz.txt'
    ]
});

There is no output from calling this function. If there is an error it will be thrown.

The API

output: String required

The path to the output folder.

If the folder doesn't exist, it will be made.

input: Array<String> required

An ordered list of paths to input folders.

The order matters: the last input will override the first, if there are files with the same name.

files: Array<String>

An unordered list of specific file paths to merge.

The Examples

Suppose you have a folder structure like this:

input
  |- 001
  |  |- aaa
  |  |  \- file.txt // "text-1"
  |  \- bbb
  |  |  \- file.txt // "text-2"
  |- 002
  |  |- aaa
  |  |  \- file.txt // "text-3"
  |  \- ccc
  |     \- file.txt // "text-4"
  \- 003
     |- bbb
     |  \- file.txt // "text-5"
     \- ccc
        \- file.txt // "text-6"

The Example 1: Merge Everything

If you wanted to merge all input folders, you would do:

await mergefs({
    output: '/output',
    input: [
        '/input/001',
        '/input/002',
        '/input/003'
    ]
});

Then the structure of the output folder would be:

output
  |- aaa
  |  \- file.txt // "text-3"
  |- bbb
  | \- file.txt // "text-5"
  \- ccc
     \- file.txt // "text-6"

The Example 2: Change Merge Order

If we take the same example but change the order of the input folders:

await mergefs({
    output: '/output',
    input: [
        '/input/003',
        '/input/002',
        '/input/001'
    ]
});

Then the structure of the output folder would be:

output
  |- aaa
  |  \- file.txt // "text-1"
  |- bbb
  | \- file.txt // "text-2"
  \- ccc
     \- file.txt // "text-4"

The Example 3: Merge Specific Files

If we take the same input folder structure but list specific files:

await mergefs({
    output: '/output',
    input: [
        '/input/001',
        '/input/002',
        '/input/003'
    ],
    files: [
        'ccc/file.txt'
    ]
});

Then the structure of the output folder would be:

output
  \- ccc
     \- file.txt // "text-6"

The Path Details

Both the input and output paths will be resolved using the builtin NodeJS path.resolve.

You can use relative or absolute paths, and they will be interpreted using that module.

The files properties will be resolved with the input paths using path.join and then path.resolve on the resulting filepath.

The License

Published and released under the Very Open License.