FileReaderSync Interface
The FileReaderSync
interface allows to read File
or Blob
objects in a synchronous way.
This interface is only available in workers as it enables synchronous I/O that could potentially block.
Constructors
Code new FileReaderSync() #
FileReaderSync();
Methods
Code ArrayBuffer readAsArrayBuffer(Blob blob) #
This method reads the contents of the specified Blob
or File
. When the read operation is finished, it returns an ArrayBuffer
representing the file's data. If an error happened during the read, the adequate exception is sent.
Parameters
blob
- The DOM
Blob
orFile
to read into theArrayBuffer
.
Return value
An ArrayBuffer
representing the file's data.
Exceptions
The following exceptions can be raised by this method:
NotFoundError
- is raised when the resource represented by the DOM
Blob
orFile
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;
- two 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.
ArrayBuffer readAsArrayBuffer(Blob blob);
Code String readAsBinaryString(Blob blob) #
This method reads the contents of the specified Blob
, which may be a File
. When the read operation is finished, it returns a DOMString
containing the raw binary data from the file. If an error happened during the read, the adequate exception is sent.
readAsArrayBuffer()
should be used instead.Return value
A
DOMString
containing the raw binary data from the resource
Exceptions
The following exceptions can be raised by this method:
NotFoundError
- is raised when the resource represented by the DOM
Blob
orFile
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;
- two 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.
String readAsBinaryString(Blob blob);
Code String readAsDataURL(Blob blob) #
This method reads the contents of the specified Blob
or File
. When the read operation is finished, it returns a data URL representing the file's data. If an error happened during the read, the adequate exception is sent.
Return value
An DOMString
representing the file's 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
Blob
orFile
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.
String readAsDataURL(Blob blob);
Code String readAsText(Blob blob, [String encoding]) #
This methods reads the specified blob's contents. When the read operation is finished, it returns a DOMString
containing the file represented as a text string. The optional encoding
parameter indicates the encoding to be used. If not present, the method will apply a detection algorithm for it. If an error happened during the read, the adequate exception is sent.
Parameters
Return value
A DOMString
containing the raw binary data from the resource
Exceptions
The following exceptions can be raised by this method:
NotFoundError
- is raised when the resource represented by the DOM
Blob
orFile
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;
- two 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.
String readAsText(Blob blob, [String encoding]);
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