The
readAsText()
method of the FileReaderSync
interface allows to read File
or Blob
objects in a synchronous way into an DOMString
. This interface is only available in workers as it enables synchronous I/O that could potentially block.Syntax
readAsText(File); readAsText(Blob); readAsText(File, encoding); readAsText(Blob, encoding);
Parameters
blob
- The DOM
File
orBlob
to read. encoding
- The optional parameter specifies encoding to be used (e.g., iso-8859-1 or UTF-8). If not present, the method will apply a detection algorithm for it.
Return value
An DOMString
representing the input data.
Exceptions
The following exceptions can be raised by this method:
NotFoundError
- is raised when the resource represented by the DOM
File
orBlob
cannot be found, e.g. because it has been erased. SecurityError
- is raised when one of the following problematic situation is detected:
- the resource has been modified by a third party;
- too many read are performed simultaneously;
- the file pointed by the resource is unsafe for a use from the Web (like it is a system file).
NotReadableError
- is raised when the resource cannot be read due to a permission problem, like a concurrent lock.
EncodingError
- is raised when the resource is a data URL and exceed the limit length defined by each browser.
Specifications
Specification | Status | Comment |
---|---|---|
File API The definition of 'readAsText' 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.
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
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 |
Legend
- Full support
- Full support