Function createLazyFile

src/piper.js:3137–3286

(parent, name, url, canRead, canWrite)

				}
			},
			createLazyFile(parent, name, url, canRead, canWrite) {
				function LazyUint8Array() {
					this.lengthKnown = false;
					this.chunks = [];
				}
				LazyUint8Array.prototype.get = function LazyUint8Array_get(idx) {
					if (idx > this.length - 1 || idx < 0) {
						return undefined;
					}
					var chunkOffset = idx % this.chunkSize;
					var chunkNum = (idx / this.chunkSize) | 0;
					return this.getter(chunkNum)[chunkOffset];
				};
				LazyUint8Array.prototype.setDataGetter = function LazyUint8Array_setDataGetter(getter) {
					this.getter = getter;
				};
				LazyUint8Array.prototype.cacheLength = function LazyUint8Array_cacheLength() {
					var xhr = new XMLHttpRequest();
					xhr.open('HEAD', url, false);
					xhr.send(null);
					if (!((xhr.status >= 200 && xhr.status < 300) || xhr.status === 304))
						throw new Error("Couldn't load " + url + '. Status: ' + xhr.status);
					var datalength = Number(xhr.getResponseHeader('Content-length'));
					var header;
					var hasByteServing =
						(header = xhr.getResponseHeader('Accept-Ranges')) && header === 'bytes';
					var usesGzip = (header = xhr.getResponseHeader('Content-Encoding')) && header === 'gzip';
					var chunkSize = 1024 * 1024;
					if (!hasByteServing) chunkSize = datalength;
					var doXHR = (from, to) => {
						if (from > to)
							throw new Error('invalid range (' + from + ', ' + to + ') or no bytes requested!');
						if (to > datalength - 1)
							throw new Error('only ' + datalength + ' bytes available! programmer error!');
						var xhr = new XMLHttpRequest();
						xhr.open('GET', url, false);
						if (datalength !== chunkSize) xhr.setRequestHeader('Range', 'bytes=' + from + '-' + to);
						xhr.responseType = 'arraybuffer';
						if (xhr.overrideMimeType) {
							xhr.overrideMimeType('text/plain; charset=x-user-defined');
						}
						xhr.send(null);
						if (!((xhr.status >= 200 && xhr.status < 300) || xhr.status === 304))
							throw new Error("Couldn't load " + url + '. Status: ' + xhr.status);
						if (xhr.response !== undefined) {
							return new Uint8Array(xhr.response || []);
						}
						return intArrayFromString(xhr.responseText || '', true);
					};
					var lazyArray = this;
					lazyArray.setDataGetter((chunkNum) => {
						var start = chunkNum * chunkSize;
						var end = (chunkNum + 1) * chunkSize - 1;
						end = Math.min(end, datalength - 1);
						if (typeof lazyArray.chunks[chunkNum] == 'undefined') {
							lazyArray.chunks[chunkNum] = doXHR(start, end);
						}
						if (typeof lazyArray.chunks[chunkNum] == 'undefined') throw new Error('doXHR failed!');