If you need to save really large files bigger then the blob's size limitation or don't have enough RAM, then have a look at the more advanced StreamSaver.js that can save data directly to the hard drive asynchronously with the power of the new streams API. That will have support for progress, cancelation and knowing when it's done writing

FileSaver.js

FileSaver.js implements the saveAs() FileSaver interface in browsers that do not natively support it. There is a FileSaver.js demo that demonstrates saving various media types.

FileSaver.js is the solution to saving files on the client-side, and is perfect for webapps that need to generate files, or for saving sensitive information that shouldn't be sent to an external server.

Looking for canvas.toBlob() for saving canvases? Check out canvas-toBlob.js for a cross-browser implementation.

Supported browsers

Browser	Constructs as	Filenames	Max Blob Size	Dependencies
Firefox 20+	Blob	Yes	800 MiB	None
Firefox < 20	data: URI	No	n/a	Blob.js
Chrome	Blob	Yes	500 MiB	None
Chrome for Android	Blob	Yes	500 MiB	None
Edge	Blob	Yes	?	None
IE 10+	Blob	Yes	600 MiB	None
Opera 15+	Blob	Yes	500 MiB	None
Opera < 15	data: URI	No	n/a	Blob.js
Safari 6.1+*	Blob	No	?	None
Safari < 6	data: URI	No	n/a	Blob.js
Safari 10.1+	Blob	Yes	n/a	None

Feature detection is possible:

try {
    var isFileSaverSupported = !!new Blob;
} catch (e) {}

IE < 10

It is possible to save text files in IE < 10 without Flash-based polyfills. See ChenWenBrian and koffsyrup's saveTextAs() for more details.

Safari 6.1+

Blobs may be opened instead of saved sometimes—you may have to direct your Safari users to manually press ⌘+S to save the file after it is opened. Using the application/octet-stream MIME type to force downloads can cause issues in Safari.

iOS

saveAs must be run within a user interaction event such as onTouchDown or onClick; setTimeout will prevent saveAs from triggering. Due to restrictions in iOS saveAs opens in a new window instead of downloading, if you want this fixed please tell Apple how this bug is affecting you.

Syntax

FileSaver saveAs(Blob/File data, optional DOMString filename, optional Boolean disableAutoBOM)

Pass true for disableAutoBOM if you don't want FileSaver.js to automatically provide Unicode text encoding hints (see: byte order mark).

Examples

Saving text using require

var FileSaver = require('file-saver');
var blob = new Blob(["Hello, world!"], {type: "text/plain;charset=utf-8"});
FileSaver.saveAs(blob, "hello world.txt");

Saving text

var blob = new Blob(["Hello, world!"], {type: "text/plain;charset=utf-8"});
FileSaver.saveAs(blob, "hello world.txt");

The standard W3C File API Blob interface is not available in all browsers. Blob.js is a cross-browser Blob implementation that solves this.

Saving a canvas

var canvas = document.getElementById("my-canvas"), ctx = canvas.getContext("2d");
// draw to canvas...
canvas.toBlob(function(blob) {
    saveAs(blob, "pretty image.png");
});

Note: The standard HTML5 canvas.toBlob() method is not available in all browsers. canvas-toBlob.js is a cross-browser canvas.toBlob() that polyfills this.

Saving File

You can save a File constructor without specifying a filename. The File itself already contains a name, There is a hand full of ways to get a file instance (from storage, file input, new constructor) But if you still want to change the name, then you can change it in the 2nd argument

var file = new File(["Hello, world!"], "hello world.txt", {type: "text/plain;charset=utf-8"});
FileSaver.saveAs(file);

Installation

npm install file-saver --save
bower install file-saver

Additionally, TypeScript definitions can be installed via:

npm install @types/file-saver --save-dev