js-untar

Library for extracting tar files in the browser. Useful when packing all your application images/sound/json/etc. data in a standard .tar file and serving to clients as one gzipped bundle.

Browser feature requirements

• Promises. See here for an IE polyfill.
• ArrayBuffer.
• Web Workers.
• Blob and the Blob() constructor.

As of September 2015 this includes Chrome>=20, Firefox>=13, IE>=10, Opera>=12.10 and Safari>=8. Web Worker transferable objects are used when available, increasing speed greatly. This is supported in Chrome>=21, Firefox>=18, Opera>=15 and Safari.

Documentation

Load the module with RequireJS or similar. The module is a function that returns a modified Promise with a progress callback. This callback is executed every time a file is extracted. The standard Promise.then method is also called when extraction is done, with all extracted files as argument. The extraction is done in a Web Worker to allow the main UI thread to continue.

Example:

define(["untar"], function(untar) {
	// Load the source ArrayBuffer from a XMLHttpRequest (or any other way you may need).
	var sourceBuffer = [...];
	
	untar(sourceBuffer)
		.progress(function(extractedFile) {
			...
		})
		.then(function(extractedFiles) {
			...
		});
	// or
	untar(sourceBuffer).then(
		function(extractedFiles) { // onSuccess
			...
		},
		function(err) { // onError
			...
		},
		function(extractedFile) { // onProgress
			...
		}
	);
});

File object

The returned file object(s) has the following properties. Most of these are explained in the Tar wikipedia entry.

• name = The full filename (including path and ustar filename prefix).
• mode
• uid
• gid
• size
• modificationTime
• checksum
• type
• linkname
• ustarFormat
• blob A Blob object with the contens of the file.
• getObjectUrl() A unique ObjectUrl to the data can be retrieved with this method for easy usage of extracted data in <img> tags etc. document.getElementById("targetImageElement").src = file.getObjectUrl();

If the .tar file was in the ustar format (which most are), the following properties are also defined:

• version
• uname
• gname
• devmajor
• devminor
• namePrefix