Overview

The Filesystem API allows developers to access the device native file system to store and retrieve assets such as images and media files. This JavaScript API provides access to read, write and navigate through the device native file system hierarchies.

Module

The classes/methods for this API belong to the Filesystem product module.

Example

The following set of code examples illustrates the most common use case scenarios of using the File API.

The examples include the following data operations:

  • creating a file,

  • writing to a file,

  • reading a file,

  • switching between catalogs.

For more code examples and detailed information refer to the W3C website.

Creating a file

var errorHandler = function(err) {
  console.log(err);
}

requestFileSystem(
  window.PERSISTENT, 
  10*1024*1024 /*10MB*/, 
  function(fs) {
    fs.root.getFile("foo.txt", { 'create' : true }, function(fileEntry) {
        console.log(fileEntry.name);
    }, errorHandler);
  }, 
  errorHandler
);

Writing to a file

var errorHandler = function(err) {
  console.log(err);
}

var blob = new Blob(["Some text"]);

requestFileSystem(
  window.PERSISTENT, 
  10*1024*1024 /*10MB*/, 
  function(fs) {
    fs.root.getFile('foo.txt', { 'create' : true }, function(fileEntry) {
      var writer = fileEntry.createWriter();
      writer.write("My example of text written to file");
      writer.onwrite = function(event) {
        console.log("Done");
      };
      writer.onerror = function(event) {
        console.log("Error occured.");
      writer.write(blob);
      }
    }, errorHandler);
  }, 
  errorHandler
);

Reading a file

var errorHandler = function(err) {
  console.log(err);
}

requestFileSystem(
  window.PERSISTENT, 
  10*1024*1024 /*10MB*/, 
  function(fs) {
    fs.root.getFile('foo.txt', {}, function(entry) {
      entry.file(function(fd) {
        var reader = new FileReader();
        reader.onload = function(event) {
          console.log("Read: " + reader.result);
        };
        reader.onerror = function(event) {
          console.log("Error occured.");
        };
        reader.readAsText(fd);
      }, errorHandler);
    }, errorHandler);
  }, 
  errorHandler
);

Switching between catalogs

var errorHandler = function(err) {
  console.log(err);
}

requestFileSystem(
  window.PERSISTENT, 
  10*1024*1024 /*10MB*/, 
  function(fs) {
    fs.root.getDirectory('foo', null, function(dirEntry) {
      dirEntry.getDirectory('bar', null, function(dirEntry) {
        dirEntry.getFile('baz', null, function(fileEntry) {
          console.log(fileEntry.name);
        }, errorHandler);
      }, errorHandler);
    }, errorHandler);
  }, 
  errorHandler
);

Related topics

Public API reference
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