JavaScript FileReaderSync : Object

constructor

Similar to FileReader except synchronously reads from Blobs. Only available inside Workers.

Spec

Constructors

new FileReaderSync() : FileReaderSync

Constructs a new FileReaderSync.

Instance Methods

readAsArrayBuffer() : ArrayBuffer

Reads from blob as an ArrayBuffer. See also Blob.arrayBuffer().

Example:

<script id='code' type='text/plain'>
  const blob = new Blob(['foo']);
  const reader = new FileReaderSync();
  postMessage(reader.readAsArrayBuffer(blob));
</script>
<script>
  var code = document.getElementById('code').textContent;
  var blob = new Blob([code], { type: 'application/javascript' });
  var url = URL.createObjectURL(blob);
  var worker = new Worker(url);
  worker.onmessage = function(e) {
    console.log('worker returned: ', ...new Uint8Array(e.data));
  };
</script>

Run

Results:

readAsText(blob : Blob, [encoding : String]) : String

Reads from blob as a string. For the valid values of encoding, see character sets. See also Blob.text().

Example:

<script id='code' type='text/plain'>
  const blob = new Blob(['foo']);
  const reader = new FileReaderSync();
  postMessage(reader.readAsText(blob));
</script>
<script>
  var code = document.getElementById('code').textContent;
  var blob = new Blob([code], { type: 'application/javascript' });
  var url = URL.createObjectURL(blob);
  var worker = new Worker(url);
  worker.onmessage = function(e) {
    console.log('worker returned: ', e.data);
  };
</script>

Run

Results:

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