seekSync method

num seekSync(Object offset, SeekMode whence)

Synchronously seek to the given offset under mode given by whence. The new position within the resource (bytes from the start) is returned.

const file = Deno.openSync(
  "hello.txt",
  { read: true, write: true, truncate: true, create: true },
);
file.writeSync(new TextEncoder().encode("Hello world"));

// advance cursor 6 bytes
const cursorPosition = file.seekSync(6, Deno.SeekMode.Start);
console.log(cursorPosition);  // 6
const buf = new Uint8Array(100);
file.readSync(buf);
console.log(new TextDecoder().decode(buf)); // "world"
file.close();

The seek modes work as follows:

// Given file.rid pointing to file with "Hello world", which is 11 bytes long:
const file = Deno.openSync(
  "hello.txt",
  { read: true, write: true, truncate: true, create: true },
);
file.writeSync(new TextEncoder().encode("Hello world"));

// Seek 6 bytes from the start of the file
console.log(file.seekSync(6, Deno.SeekMode.Start)); // "6"
// Seek 2 more bytes from the current position
console.log(file.seekSync(2, Deno.SeekMode.Current)); // "8"
// Seek backwards 2 bytes from the end of the file
console.log(file.seekSync(-2, Deno.SeekMode.End)); // "9" (i.e. 11-2)
file.close();

Implementation

_i2.num seekSync(
  _i2.Object offset,
  _i4.SeekMode whence,
) =>
    _i3.callMethod(
      this,
      'seekSync',
      [
        offset,
        whence.name,
      ],
    );