The FileReader result property returns the file's contents. This property is only valid after the read operation is complete, and the format of the data depends on which of the methods was used to initiate the read operation.


var file = instanceOfFileReader.result


An appropiate string or ArrayBuffer based on which of the reading methods was used to initiate the read operation. The value is null if the reading is not yet complete or was unsuccessful.

The result types are described below.

Method Description
readAsArrayBuffer() The result is a JavaScript ArrayBuffer containing binary data.
readAsBinaryString() The result contains the raw binary data from the file in a string.
readAsDataURL() The result is a string with a data: URL representing the file's data.
readAsText() The result is text in a string.


This example presents a function, read(), which reads a file from a file input. It works by creating a FileReader object and creating a listener for load events such that when then file is read, the result is obtained and passed to the callback function provided to read().

The content is handled as raw text data.

var fileInput = document.querySelector('input[type="file"]');

function read(callback) {
  var file = fileInput.files.item(0);
  var reader = new FileReader();

  reader.onload = function() {



Specification Status Comment
File API
The definition of 'result' in that specification.
Working Draft Initial definition

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
resultChrome Full support 7Edge Full support 12Firefox Full support 3.6IE Full support 10Opera Full support 11Safari Full support 6WebView Android Full support YesChrome Android Full support YesFirefox Android Full support 32Opera Android Full support 11Safari iOS Full support 6.1Samsung Internet Android Full support Yes


Full support  
Full support

See also