method Buffer.subarray
Usage in Deno
import { type Buffer } from "node:buffer";
Buffer.subarray(start?: number,end?: number,): Buffer
Returns a new Buffer
that references the same memory as the original, but
offset and cropped by the start
and end
indices.
Specifying end
greater than buf.length
will return the same result as
that of end
equal to buf.length
.
This method is inherited from TypedArray.prototype.subarray()
.
Modifying the new Buffer
slice will modify the memory in the original Buffer
because the allocated memory of the two objects overlap.
import { Buffer } from 'node:buffer'; // Create a `Buffer` with the ASCII alphabet, take a slice, and modify one byte // from the original `Buffer`. const buf1 = Buffer.allocUnsafe(26); for (let i = 0; i < 26; i++) { // 97 is the decimal ASCII value for 'a'. buf1[i] = i + 97; } const buf2 = buf1.subarray(0, 3); console.log(buf2.toString('ascii', 0, buf2.length)); // Prints: abc buf1[0] = 33; console.log(buf2.toString('ascii', 0, buf2.length)); // Prints: !bc
Specifying negative indexes causes the slice to be generated relative to the
end of buf
rather than the beginning.
import { Buffer } from 'node:buffer'; const buf = Buffer.from('buffer'); console.log(buf.subarray(-6, -1).toString()); // Prints: buffe // (Equivalent to buf.subarray(0, 5).) console.log(buf.subarray(-6, -2).toString()); // Prints: buff // (Equivalent to buf.subarray(0, 4).) console.log(buf.subarray(-5, -2).toString()); // Prints: uff // (Equivalent to buf.subarray(1, 4).)