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.
Syntax
var file = instanceOfFileReader.result
Value
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. |
Example
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() { callback(reader.result); } reader.readAsText(file); }
Specifications
Specification | Status | Comment |
---|---|---|
File API The definition of 'result' in that specification. |
Working Draft | Initial definition |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
result | Chrome Full support 7 | Edge Full support 12 | Firefox Full support 3.6 | IE Full support 10 | Opera Full support 11 | Safari Full support 6 | WebView Android Full support Yes | Chrome Android Full support Yes | Firefox Android Full support 32 | Opera Android Full support 11 | Safari iOS Full support 6.1 | Samsung Internet Android Full support Yes |
Legend
- Full support
- Full support