Blob.js
An HTML5 Blob implementation
...The library detects available browser capabilities and can fall back to vendor-specific BlobBuilder implementations when necessary. Its broader implementation also supplies compatible File, FileReader, and object URL behavior for older environments. Blob instances can expose size and media type information, create slices, and be read as text or array buffers. It is most useful for legacy web applications that generate files, process binary content, or work with client-side downloads.