This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the specification changes.
Non-standard
This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.
The FileSystemFileEntry
interface's method createWriter()
returns a FileWriter
object which can be used to write data into the file represented by the directory entry.
Syntax
FileSystemFileEntry.createWriter(successCallback[, errorCallback]);
Parameters
successCallback
- A callback function which is called when the
FileWriter
has been created successfully; theFileWriter
is passed into the callback as the only parameter. errorCallback
Optional- If provided, this must be a method which is caled when an error occurs while trying to create the
FileWriter
. This callback receives as input aFileError
object describing the error.
Editor's note: We need to find out what kinds of errors can occur and document them.
Return value
Example
This example establishes a method, writeToFileEntry()
, which outputs a text string to the file corresponding to the passed-in directory entry.
function writeToFileEntry(entry, text) { entry.createWriter(function(fileWriter)) { let data = Blob([text], { type: "text/plain" }); fileWriter.write(data); }, function(fileError) { /* do whatever to handle the error */ }); }
The success callback for the createWriter()
call takes the text which was passed in and creates a new Blob
object of type text/plain
that contains the passed text. This blob is then output to the FileWriter
object to be written to the file.
Specifications
Specification | Status | Comment |
---|---|---|
File and Directory Entries API The definition of 'createWriter()' in that specification. |
Editor's Draft | Initial specification. |
This API has no official W3C or WHATWG specification.
In addition, this method doesn't even exist in the most recent draft of the File and Directory Entries API draft specification.
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 13 webkit | No support[1] | No support | No support | No support |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | No support | 0.16webkit | No support[1] | No support | No support | No support |
[1] While the createWriter()
method exists in Firefox 50, it is not supported, and immediately reports an NS_ERROR_DOM_SECURITY_ERR
error to the error callback.