license: Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

     Unless required by applicable law or agreed to in writing,
     software distributed under the License is distributed on an
     "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
     KIND, either express or implied.  See the License for the
     specific language governing permissions and limitations
     under the License.

FileReader

FileReader is an object that allows one to read a file.

Properties

readyState: One of the three states the reader can be in EMPTY, LOADING or DONE.
result: The contents of the file that has been read. (DOMString)
error: An object containing errors. (FileError)
onloadstart: Called when the read starts. . (Function)
onprogress: Called while reading the file, reports progress (progess.loaded/progress.total). (Function) -NOT SUPPORTED
onload: Called when the read has successfully completed. (Function)
onabort: Called when the read has been aborted. For instance, by invoking the abort() method. (Function)
onerror: Called when the read has failed. (Function)
onloadend: Called when the request has completed (either in success or failure). (Function)

Methods

abort: Aborts reading file.
readAsDataURL: Read file and return data as a base64 encoded data url.
readAsText: Reads text file.
readAsBinaryString: Reads file as binary and returns a binary string.
readAsArrayBuffer: Reads file as an ArrayBuffer.

Details

The FileReader object is a way to read files from the devices file system. Files can be read as text or as a base64 data encoded string. Users register their own event listeners to receive the loadstart, progress, load, loadend, error and abort events.

Supported Platforms

Android
BlackBerry WebWorks (OS 5.0 and higher)
iOS
Windows Phone 7 and 8
Windows 8

Read As Data URL

Parameters:

file - the file object to read

Quick Example

function win(file) {
	var reader = new FileReader();
	reader.onloadend = function(evt) {
    	console.log("read success");
        console.log(evt.target.result);
    };
	reader.readAsDataURL(file);
};

var fail = function(evt) {
	console.log(error.code);
};

entry.file(win, fail);

Read As Text

Parameters:

file - the file object to read
encoding - the encoding to use to encode the file's content. Default is UTF8.

Quick Example

function win(file) {
	var reader = new FileReader();
	reader.onloadend = function(evt) {
    	console.log("read success");
        console.log(evt.target.result);
    };
	reader.readAsText(file);
};

var fail = function(evt) {
	console.log(error.code);
};

entry.file(win, fail);

Abort Quick Example

function win(file) {
	var reader = new FileReader();
	reader.onloadend = function(evt) {
    	console.log("read success");
        console.log(evt.target.result);
    };
	reader.readAsText(file);
	reader.abort();
};

function fail(error) {
	console.log(error.code);
}

entry.file(win, fail);

Full Example

<!DOCTYPE html>
<html>
  <head>
    <title>FileReader Example</title>

    <script type="text/javascript" charset="utf-8" src="cordova-x.x.x.js"></script>
    <script type="text/javascript" charset="utf-8">

    // Wait for Cordova to load
    //
    function onLoad() {
        document.addEventListener("deviceready", onDeviceReady, false);
    }

    // Cordova is ready
    //
    function onDeviceReady() {
		window.requestFileSystem(LocalFileSystem.PERSISTENT, 0, gotFS, fail);
    }
	
	function gotFS(fileSystem) {
		fileSystem.root.getFile("readme.txt", null, gotFileEntry, fail);
	}
	
	function gotFileEntry(fileEntry) {
		fileEntry.file(gotFile, fail);
	}
	
    function gotFile(file){
		readDataUrl(file);
		readAsText(file);
	}
    
    function readDataUrl(file) {
        var reader = new FileReader();
        reader.onloadend = function(evt) {
            console.log("Read as data URL");
            console.log(evt.target.result);
        };
        reader.readAsDataURL(file);
    }
    
    function readAsText(file) {
        var reader = new FileReader();
        reader.onloadend = function(evt) {
            console.log("Read as text");
            console.log(evt.target.result);
        };
        reader.readAsText(file);
    }
    
    function fail(evt) {
        console.log(evt.target.error.code);
    }
    
    </script>
  </head>
  <body>
    <h1>Example</h1>
    <p>Read File</p>
  </body>
</html>

iOS Quirks

encoding parameter is not supported, UTF8 encoding is always used.

Read As Binary String

Currently supported on iOS and Android only.

Parameters:

file - the file object to read

Quick Example

function win(file) {
	var reader = new FileReader();
	reader.onloadend = function(evt) {
    	console.log("read success");
        console.log(evt.target.result);
    };
	reader.readAsBinaryString(file);
};

var fail = function(evt) {
	console.log(error.code);
};

entry.file(win, fail);

Read As Array Buffer

Currently supported on iOS and Android only.

Parameters:

file - the file object to read

Quick Example

function win(file) {
	var reader = new FileReader();
	reader.onloadend = function(evt) {
    	console.log("read success");
        console.log(new Uint8Array(evt.target.result));
    };
	reader.readAsArrayBuffer(file);
};

var fail = function(evt) {
	console.log(error.code);
};

entry.file(win, fail);