FileSystemFileEntry.file()
The FileSystemFileEntry
interface's method
file()
returns a
File
object which can be used to read data from the file represented by
the directory entry.
Syntax
FileSystemFileEntry.file(successCallback[, errorCallback]);
Parameters
successCallback
-
A callback function which is called when the
File
has been created successfully; theFile
is passed into the callback as the only parameter. errorCallback
Optional-
If provided, this must be a method which is called when an error occurs while trying to create the
File
. This callback receives as input aDOMException
object describing the error.
Return value
Example
This example establishes a method, readFile()
, reads a text file and calls
a specified callback function with the received text (in a String
object)
once the read is completed. If an error occurs, a specified (optional) error callback is
called.
function readFile(entry, successCallback, errorCallback) {
entry.file(function(file) {
let reader = new FileReader();
reader.onload = function() {
successCallback(reader.result);
};
reader.onerror = function() {
errorCallback(reader.error);
}
reader.readAsText(file);
}, errorCallback);
}
This function calls file()
, specifying as its success callback a method
which proceeds to use a FileReader
to read the file as text. The
FileReader's load
event handler is set up to deliver the loaded string to
the successCallback
specified when the readFile()
method was
called; similarly, its error
handler is set up to call the
errorCallback
specified.
Specifications
Specification |
---|
File and Directory Entries API # dom-filesystemfileentry-file |
Browser compatibility
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