extract-files

A function to recursively extract files and their object paths within a value, replacing them with null in a deep clone without mutating the original value. FileList instances are treated as File instance arrays. Files are typically File and Blob instances.

Used by GraphQL multipart request spec client implementations such as graphql-react and apollo-upload-client.

Installation

To install with npm, run:

npm install extract-files

See the documentation for the function extractFiles to get started.

Requirements

• Node.js: ^12.22.0 || ^14.17.0 || >= 16.0.0
• Browsers: > 0.5%, not OperaMini all, not IE > 0, not dead

Exports

These ECMAScript modules are published to npm and exported via the package.json exports field:

• extractFiles.mjs
• isExtractableFile.mjs

extractFiles.mjs

Export default

Function extractFiles — Recursively extracts files and their object paths within a value, replacing them with null in a deep clone without mutating the original value. FileList instances are treated as File instance arrays.

Type parameters

1. Extractable: any — Extractable file type.

Parameters

1. value: unknown — Value to extract files from. Typically an object tree.
2. isExtractable: (value: unknown) => value is Extractable — Matches extractable files. Typically isExtractableFile.
3. path ?: ObjectPath — Prefix for object paths for extracted files. Defaults to "".

Returns

Extraction<Extractable> — Extraction result.

Example 1

Extracting files from an object.

For the following:

import extractFiles from "extract-files/extractFiles.mjs";
import isExtractableFile from "extract-files/isExtractableFile.mjs";

const file1 = new File(["1"], "1.txt", { type: "text/plain" });
const file2 = new File(["2"], "2.txt", { type: "text/plain" });
const value = {
  a: file1,
  b: [file1, file2],
};

const { clone, files } = extractFiles(value, isExtractableFile, "prefix");

value remains the same.

clone is:

{
  "a": null,
  "b": [null, null]
}

files is a Map instance containing:

Key	Value
file1	["prefix.a", "prefix.b.0"]
file2	["prefix.b.1"]

Type Extraction

object — An extraction result.

Type parameters

1. Extractable ?: any — Extractable file type. Defaults to unknown.

Properties

• clone: unknown — Clone of the original value with files recursively replaced with null.
• files: Map<Extractable, Array<ObjectPath>> — Extracted files and their object paths within the original value.

Type ObjectPath

string — String notation for the path to a node in an object tree.

See

• object-path on npm.

Example 1

An object path for object property a, array index 0, object property b:

a.0.b

isExtractableFile.mjs

Export default

Function isExtractableFile — Checks if a value is an extractable file.

Parameters

1. value: unknown — Value to check.

Returns

value is ExtractableFile — Is the value an extractable file.

Type ExtractableFile

File | Blob — An extractable file.