This is an experimental feature
Because this feature is still in development in some browsers, check the compatibility table for the proper prefixes to use in various browsers.
An easy way to construct a Blob is by using the BlobBuilder interface, which lets you iteratively append data to a blob, then retrieve the completed blob when you're ready to use it for something. Another way is to use the slice() method to create a blob that contains a subset of another blob's data.
Documentation for this class was provided by MDN. var size(default,null) : IntThe size, in bytes, of the data contained in the Blob object. Read only. var type(default,null) : StringAn ASCII-encoded string, in all lower case, indicating the MIME type of the data contained in the Blob. If the type is unknown, this string is empty. Read only. function new( ?arg0 : Dynamic, ?arg1 : Dynamic ) : Void function slice( ?start : Int, ?end : Int, ?contentType : String ) : Blob