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createBlobFromRandomAccessStream method

Creates a Blob from an IRandomAccessStream object. This method should be used when dealing with IRandomAccessStream objects in Apps in order to create a W3C based object from the stream. Once the blob is created, it can be used with the FileReader, URL APIs, and XMLHttpRequest. .

Internet Explorer 10



var retVal = MSApp.createBlobFromRandomAccessStream(type, stream);


  • type [in]
    Type: String

    Content type of the data. This string should be in the format specified in the media-type token defined in section 3.7 of RFC 2616.

  • stream [in]
    Type: any

    IRandomAccessStream to be stored in the Blob.

Return value

Type: Blob

New blob object that contains the stream


Exception Condition

The node type is incompatible with the expected parameter type. For versions earlier than Internet Explorer 10, TYPE_MISMATCH_ERR is returned.



Creates a Blobfrom Windows Runtime types via the MSApp namespace on the window object. This method will create a blob that is essentially a light wrapper over the RandomAccessStream object provided to it. The blob owns the lifetime of this stream and the stream will be closed when the blob is destroyed.


var randomAccessStream = dataPackage.GetData("image/bmp");
var blob = window.MSApp.createBlobFromRandomAccessStream("image/bmp", randomAccessStream);
var url = window.URL.createObjectURL(blob, {oneTimeOnly:true});

document.getElementById("imagetag").src = url; 

See also