digitalMen/utils/download.js

(function(root, factory) {
	if (typeof define === 'function' && define.amd) {
		// AMD. Register as an anonymous module.
		define([], factory);
	} else if (typeof exports === 'object') {
		// Node. Does not work with strict CommonJS, but
		// only CommonJS-like environments that support module.exports,
		// like Node.
		module.exports = factory();
	} else {
		// Browser globals (root is window)
		root.download = factory();
	}
}(this, function() {

	return function download(data, strFileName, strMimeType) {

		var self = window, // this script is only for browsers anyway...
			defaultMime = "application/octet-stream", // this default mime also triggers iframe downloads
			mimeType = strMimeType || defaultMime,
			payload = data,
			url = !strFileName && !strMimeType && payload,
			anchor = document.createElement("a"),
			toString = function(a) {
				return String(a);
			},
			myBlob = (self.Blob || self.MozBlob || self.WebKitBlob || toString),
			fileName = strFileName || "download",
			blob,
			reader;
		myBlob = myBlob.call ? myBlob.bind(self) : Blob;

		if (String(this) ===
			"true") { //reverse arguments, allowing download.bind(true, "text/xml", "export.xml") to act as a callback
			payload = [payload, mimeType];
			mimeType = payload[0];
			payload = payload[1];
		}


		if (url && url.length <
			2048) { // if no filename and no mime, assume a url was passed as the only argument
			fileName = url.split("/").pop().split("?")[0];
			anchor.href = url; // assign href prop to temp anchor
			if (anchor.href.indexOf(url) !== -
				1) { // if the browser determines that it's a potentially valid url path:
				var ajax = new XMLHttpRequest();
				ajax.open("GET", url, true);
				ajax.responseType = 'blob';
				ajax.onload = function(e) {
					download(e.target.response, fileName, defaultMime);
				};
				setTimeout(function() {
					ajax.send();
				}, 0); // allows setting custom ajax headers using the return:
				return ajax;
			} // end if valid url?
		} // end if url?


		//go ahead and download dataURLs right away
		if (/^data\:[\w+\-]+\/[\w+\-]+[,;]/.test(payload)) {

			if (payload.length > (1024 * 1024 * 1.999) && myBlob !== toString) {
				payload = dataUrlToBlob(payload);
				mimeType = payload.type || defaultMime;
			} else {
				return navigator.msSaveBlob ? // IE10 can't do a[download], only Blobs:
					navigator.msSaveBlob(dataUrlToBlob(payload), fileName) :
					saver(payload); // everyone else can save dataURLs un-processed
			}

		} //end if dataURL passed?

		blob = payload instanceof myBlob ?
			payload :
			new myBlob([payload], {
				type: mimeType
			});


		function dataUrlToBlob(strUrl) {
			var parts = strUrl.split(/[:;,]/),
				type = parts[1],
				decoder = parts[2] == "base64" ? atob : decodeURIComponent,
				binData = decoder(parts.pop()),
				mx = binData.length,
				i = 0,
				uiArr = new Uint8Array(mx);

			for (i; i < mx; ++i) uiArr[i] = binData.charCodeAt(i);

			return new myBlob([uiArr], {
				type: type
			});
		}

		function saver(url, winMode) {

			if ('download' in anchor) { //html5 A[download]
				anchor.href = url;
				anchor.setAttribute("download", fileName);
				anchor.className = "download-js-link";
				anchor.innerHTML = "downloading...";
				anchor.style.display = "none";
				document.body.appendChild(anchor);
				setTimeout(function() {
					anchor.click();
					document.body.removeChild(anchor);
					if (winMode === true) {
						setTimeout(function() {
							self.URL.revokeObjectURL(anchor.href);
						}, 250);
					}
				}, 66);
				return true;
			}

			// handle non-a[download] safari as best we can:
			if (/(Version)\/(\d+)\.(\d+)(?:\.(\d+))?.*Safari\//.test(navigator.userAgent)) {
				url = url.replace(/^data:([\w\/\-\+]+)/, defaultMime);
				if (!window.open(url)) { // popup blocked, offer direct download:
					if (confirm(
							"Displaying New Document\n\nUse Save As... to download, then click back to return to this page."
							)) {
						location.href = url;
					}
				}
				return true;
			}

			//do iframe dataURL download (old ch+FF):
			var f = document.createElement("iframe");
			document.body.appendChild(f);

			if (!winMode) { // force a mime that will download:
				url = "data:" + url.replace(/^data:([\w\/\-\+]+)/, defaultMime);
			}
			f.src = url;
			setTimeout(function() {
				document.body.removeChild(f);
			}, 333);

		} //end saver




		if (navigator.msSaveBlob) { // IE10+ : (has Blob, but not a[download] or URL)
			return navigator.msSaveBlob(blob, fileName);
		}

		if (self.URL) { // simple fast and modern way using Blob and URL:
			saver(self.URL.createObjectURL(blob), true);
		} else {
			// handle non-Blob()+non-URL browsers:
			if (typeof blob === "string" || blob.constructor === toString) {
				try {
					return saver("data:" + mimeType + ";base64," + self.btoa(blob));
				} catch (y) {
					return saver("data:" + mimeType + "," + encodeURIComponent(blob));
				}
			}

			// Blob but not URL support:
			reader = new FileReader();
			reader.onload = function(e) {
				saver(this.result);
			};
			reader.readAsDataURL(blob);
		}
		return true;
	}; /* end download() */
}));