zip.js

!function(exports, unescape, encodeURIComponent, Uint8Array) {
	/* globals Blob, Promise, Response */

	exports.createZip = createZip

	function createZip(files, next) {
		var i = 256, j, k, offset = 0
		, crcTable = []
		, cd = ""
		, ent = []
		, CompressionStream = (exports.window || global).CompressionStream
		, compress = CompressionStream ? function(uint, cb) {
			new Response(
				new Blob([uint]).stream().pipeThrough(new CompressionStream("deflate"))
			).arrayBuffer().then(function(arr) {
				if (uint.length > arr.byteLength - 6) cb(new Uint8Array(arr).subarray(2, -4), "\10\0")
				else cb(uint, "\0\0")
			})
		} : function(uint, cb) {
			cb(uint, "\0\0")
		}
		, now = Date.now()

		for (; i; crcTable[i] = k) {
			k = --i
			for (j = 8; j--; ) k = (k & 1) ? 0xedb88320 ^ (k >>> 1) : (k >>> 1)
		}

		if (!next) return new Promise(add)
		add(next.bind(next, null))

		function add(resolve) {
			k = files[i]
			if (!k) {
				k = files.length
				ent.push(toUint(cd + le32(0x06054b50) + le32(0) + le32((k<<16) + k) + le32(cd.length) + le32(offset) + "\0\0"))
				return resolve(new Blob(ent, { type: "application/zip" }))
			}
			var name = unescape(encodeURIComponent(k.name))
			, file = k.content
			, nameLen = name.length
			, crc = -1

			if (typeof file === "string") file = toUint(unescape(encodeURIComponent(file)))
			var rawSize = file.length
			, time = dosDate(new Date(k.time || now))

			for (j = 0; j < rawSize; ) {
				crc = (crc >>> 8) ^ crcTable[(crc ^ file[j++]) & 0xff]
			}
			compress(file, function(compressed, method) {
				var header = le32(20 | 1<<27) + method + le32(time) + le32(-1^crc >>> 0) + le32(compressed.length) + le32(rawSize) + le32(nameLen)
				ent.push(toUint("PK\3\4" + header + name), compressed)
				cd += "PK\1\2\0\24" + header + "\0\0" + le32(0) + le32(32) + le32(offset) + name
				i++
				offset += 30 + compressed.length + nameLen
				add(resolve)
			})
		}
	}

	function dosDate(date) {
		return date.getSeconds() >> 1 | date.getMinutes() << 5 | date.getHours() << 11 | date.getDate() << 16 | (date.getMonth() + 1) << 21 | (date.getFullYear() - 1980) << 25
	}
	function le32(n) {
		return String.fromCharCode.call(null, n & 0xff, (n >>> 8) & 0xff, (n >>> 16) & 0xff, (n >>> 24) & 0xff)
	}

	function toUint(str) {
		for (var i = str.length, arr = new Uint8Array(i); i--; arr[i] = str.charCodeAt(i));
		return arr
	}
}(this, unescape, encodeURIComponent, Uint8Array) // jshint ignore:line