method Deno.FsFile.prototype.seekSync
FsFile.prototype.seekSync(offset: number | bigint,whence: SeekMode,): number
Synchronously seek to the given offset under mode given by whence.
The new position within the resource (bytes from the start) is returned.
using 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"
The seek modes work as follows:
// Given the file contains "Hello world" text, which is 11 bytes long:
using 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)
whence: SeekMode
number