Improve zip documentation about fflate

[101arrowz]

To zip a file (like in your first link):

const result = fflate.zipSync({ 'log.txt': fflate.strToU8('some text') });

// convert to a blob if you need
const resultBlob = new Blob([result]);

To unzip (like in your other link):

const zipData = new Uint8Array(await yourBlob.arrayBuffer());
const files = fflate.unzipSync(zipData, {
  filter: file => file.name.startsWith("styles/") && file.name.endsWith(".json")
});

for (const fileName in files) {
  const styleText = fflate.strFromU8(files[fileName]);
  // do whatever you want here
}

If you care about not blocking the main thread, you can replace the zipSync or unzipSync calls with zip or unzip, e.g.

// first example
const result = await new Promise((resolve, reject) => fflate.zip(
   { 'log.txt': fflate.strToU8('some text') },
  (err, result) => err ? reject(err) : resolve(result)
);

// second example
const files = await new Promise((resolve, reject) => fflate.unzip(zipData, {
  filter: file => file.name.startsWith("styles/") && file.name.endsWith(".json")
}, (err, result) => err ? reject(err) : resolve(result)));

For reference, the ZIP documentation is quite thorough; you may have been looking in the wrong place.

From the README (click to expand)

// Note that the asynchronous version (see below) runs in parallel and
// is *much* (up to 3x) faster for larger archives.
const zipped = fflate.zipSync({
  // Directories can be nested structures, as in an actual filesystem
  'dir1': {
    'nested': {
      // You can use Unicode in filenames
      '你好.txt': fflate.strToU8('Hey there!')
    },
    // You can also manually write out a directory path
    'other/tmp.txt': new Uint8Array([97, 98, 99, 100])
  },

  // You can also provide compression options
  'massiveImage.bmp': [aMassiveFile, {
    level: 9,
    mem: 12
  }],
  // PNG is pre-compressed; no need to waste time
  'superTinyFile.png': [aPNGFile, { level: 0 }],

  // Directories take options too
  'exec': [{
    'hello.sh': [fflate.strToU8('echo hello world'), {
      // ZIP only: Set the operating system to Unix
      os: 3,
      // ZIP only: Make this file executable on Unix
      attrs: 0o755 << 16
    }]
  }, {
    // ZIP and GZIP support mtime (defaults to current time)
    mtime: new Date('10/20/2020')
  }]
}, {
  // These options are the defaults for all files, but file-specific
  // options take precedence.
  level: 1,
  // Obfuscate last modified time by default 
  mtime: new Date('1/1/1980')
});

// If you write the zipped data to myzip.zip and unzip, the folder
// structure will be outputted as:

// myzip.zip (original file)
// dir1
// |-> nested
// |   |-> 你好.txt
// |-> other
// |   |-> tmp.txt
// massiveImage.bmp
// superTinyFile.png

// When decompressing, folders are not nested; all filepaths are fully
// written out in the keys. For example, the return value may be:
// { 'nested/directory/structure.txt': Uint8Array(2) [97, 97] }
const decompressed = fflate.unzipSync(zipped, {
  // You may optionally supply a filter for files. By default, all files in a
  // ZIP archive are extracted, but a filter can save resources by telling
  // the library not to decompress certain files
  filter(file) {
    // Don't decompress the massive image or any files larger than 10 MiB
    return file.name != 'massiveImage.bmp' && file.originalSize <= 10_000_000;
  }
});