Web/API/FileReaderSync

The FileReaderSync interface allows to read File or Blob objects synchronously.

This interface is only available in workers as it enables synchronous I/O that could potentially block.

Properties

This interface does not have any properties.

Methods

FileReaderSync.readAsArrayBuffer()

This method converts a specified Blob or a File into an ArrayBuffer representing the input data as a binary string.

FileReaderSync.readAsBinaryString() '

This method converts a specified Blob or a File into a DOMString representing the input data as a binary string. This method is deprecated, consider using readAsArrayBuffer() instead.

FileReaderSync.readAsText()

This method converts a specified Blob or a File into a DOMString representing the input data as a text string. The optional encoding parameter indicates the encoding to be used (e.g., iso-8859-1 or UTF-8). If not present, the method will apply a detection algorithm for it.

FileReaderSync.readAsDataURL()

This method converts a specified Blob or a File into a DOMString representing the input data as a data URL.

Specifications

Specification	Status	Comment
File APIThe definition of 'FileReaderSync' in that specification.	Working Draft	Initial definition.

Browser Compatibility

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
FileReaderSync	Chrome Full support Yes	Edge Full support 12	Firefox Full support 8	IE Full support Yes	Opera Full support Yes	Safari Full support Yes	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android Full support 8	Opera Android Full support Yes	Safari iOS Full support Yes	Samsung Internet Android Full support Yes
readAsArrayBuffer	Chrome Full support Yes	Edge Full support 12	Firefox Full support 8	IE Full support Yes	Opera Full support Yes	Safari Full support Yes	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android Full support 8	Opera Android Full support Yes	Safari iOS Full support Yes	Samsung Internet Android Full support Yes
readAsBinaryString	Chrome Full support Yes	Edge Full support 12	Firefox Full support 8	IE Full support Yes	Opera Full support Yes	Safari Full support Yes	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android Full support 8	Opera Android Full support Yes	Safari iOS Full support Yes	Samsung Internet Android Full support Yes
readAsDataURL	Chrome Full support Yes	Edge Full support 12	Firefox Full support 8	IE Full support Yes	Opera Full support Yes	Safari Full support Yes	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android Full support 8	Opera Android Full support Yes	Safari iOS Full support Yes	Samsung Internet Android Full support Yes
readAsText	Chrome Full support Yes	Edge Full support 12	Firefox Full support 8	IE Full support Yes	Opera Full support Yes	Safari Full support Yes	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android Full support 8	Opera Android Full support Yes	Safari iOS Full support Yes	Samsung Internet Android Full support Yes
Service workers support Deprecated'Non-standard'	Chrome No support ? — 59	Edge ?	Firefox No support ? — 61	IE No support No	Opera No support ? — 46	Safari No support No	WebView Android No support ? — 59	Chrome Android No support ? — 59	Firefox Android No support ? — 61	Opera Android No support ? — 43	Safari iOS No support No	Samsung Internet Android No support ? — 7.0
Available in workers	Chrome Full support Yes	Edge Full support 12	Firefox Full support 8	IE Full support Yes	Opera Full support Yes	Safari Full support Yes	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android Full support 8	Opera Android Full support Yes	Safari iOS Full support Yes	Samsung Internet Android Full support Yes

Legend

Full support  

Full support

No support  

No support

Compatibility unknown  

Compatibility unknown

Non-standard. Expect poor cross-browser support.'

Non-standard. Expect poor cross-browser support.

Deprecated. Not for use in new websites.'

Deprecated. Not for use in new websites.

See also

• FileReader
• BlobBuilder, Blob
• File
• FileReader

FileReaderSync by Mozilla Contributors is licensed under CC-BY-SA 2.5.