file-type-ext

An extension to file-type lib with additional supports for .doc, .xls, .ppt

For none ms office files, it works same as file-type, but for these ancient file types, it provides additional check based on http://fileformats.archiveteam.org/wiki/Microsoft_Compound_File.

Install

$ npm install file-type-ext

Usage

From a stream, file-type-ext uses the same interface as file-type

const stream = require('stream');
const fs = require('fs');
const fileType = require('file-type-ext');

(async () => {
    const read = fs.createReadStream('sample.doc');
    const stream = await fileType.stream(read);

    console.log(stream.fileType);
    //=> {ext: 'doc', mime: 'application/msword'}

    const write = fs.createWriteStream(`output.doc`);
    stream.pipe(write);
})();

From a chunk buffer, since the CLSID, which is required to identify the ancient ms office file types, may located at anywhere in the file, it requires to load almost the entire file.

Therefore, if you would like to use the chunk buffer method, there are two options:

1, load the entire file

const readChunk = require('read-chunk');
const fs = require("fs");
const fileType = require('file-type-ext');

const stats = fs.statSync("sample.doc");
const buffer = readChunk.sync('sample.doc', 0, stats.size);

var type = fileType(buffer);
console.log(type);
//=> {ext: 'doc', mime: 'application/msword'}

2, or, check it twice with a small buffer:

const readChunk = require('read-chunk');
const fileType = require('file-type-ext');

// the first part is same as `file-type`:
var buffer = readChunk.sync('sample.doc', 0, fileType.minimumBytes);
var type = fileType(buffer);

console.log(type);
//=> { ext: 'msi', mime: 'application/x-msi', minimumRequiredBytes: 12384 }

// if the file is one of the ancient ms office file, and the buffer provided is not enough to identify the type, an extra field `minimumRequiredBytes` will be returned.

if (type.minimumRequiredBytes) {
  buffer = readChunk.sync('sample.doc', 0, type.minimumRequiredBytes);
  type = fileType(buffer);
}
console.log(type);
//=> { ext: 'doc', mime: 'application/msword' }