FileReader — asynchronously read a File or Blob
A FileReader defines an asynchronous API for reading the content of a File or any Blob. To read a file, follow these steps:
Create a FileReader with the
Define whichever event handlers you need.
Pass your File or Blob object to one of the four read methods.
onloadhandler is triggered, the file contents are available as the
resultproperty. Or, if the
onerrorhandler is triggered, the
errorproperty refers to a FileError object that provides more information.
When the read is complete, you can reuse the FileReader object or discard it and create new ones as needed.
See FileReaderSync for a synchronous API that you can use in worker threads.
Create a new FileReader object with the
FileReader() constructor, which expects no
These constants are the values of the
No read method has been called yet.
A read is in progress.
A read has completed successfully or with an error.
If an error occurs during a read, this property will refer to a FileError that describes the error.
readonly unsigned short
This property describes the current state of the FileReader. Its value will be one of the three constants listed above.
If the read completed successfully, this property will hold the File ...