FileReaderSync.readAsDataURL()

The readAsDataURL() method of the FileReaderSync interface allows to read File or Blob objects in a synchronous way into an DOMString representing a data URL. This interface is only available in workers as it enables synchronous I/O that could potentially block.

Syntax

readAsDataURL(File);
readAsDataURL(Blob);

Parameters

blob
The DOM File or Blob to read.

Return value

An DOMString representing the input data as a data URL.

Exceptions

The following exceptions can be raised by this method:

NotFoundError
is raised when the resource represented by the DOM File or Blob cannot be found, e.g. because it has been erased.
SecurityError
is raised when one of the following problematic situation is detected:
  • the resource has been modified by a third party;
  • too many read are performed simultaneously;
  • the file pointed by the resource is unsafe for a use from the Web (like it is a system file).
NotReadableError
is raised when the resource cannot be read due to a permission problem, like a concurrent lock.
EncodingError
is raised when the resource is a data URL and exceed the limit length defined by each browser.

Specifications

Specification Status Comment
File API
The definition of 'readAsDataURL' in that specification.
Working Draft Initial definition.

Browser Compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
readAsDataURLChrome Full support YesEdge Full support 12Firefox Full support 8IE Full support YesOpera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesFirefox Android Full support 8Opera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yes

Legend

Full support  
Full support

See also