nodejs · nodejs-github-bot · Mar 27, 2026 · Feb 17, 2026 · Feb 17, 2026 · Feb 18, 2026
diff --git a/benchmark/buffers/buffer-bytelength-string.js b/benchmark/buffers/buffer-bytelength-string.js
@@ -4,7 +4,7 @@ const common = require('../common');
 const bench = common.createBenchmark(main, {
   type: ['one_byte', 'two_bytes', 'three_bytes',
          'four_bytes', 'latin1'],
-  encoding: ['utf8', 'base64'],
+  encoding: ['utf8', 'base64', 'latin1', 'hex'],
   repeat: [1, 2, 16, 256], // x16
   n: [4e6],
 });

diff --git a/benchmark/buffers/buffer-copy-bytes-from.js b/benchmark/buffers/buffer-copy-bytes-from.js
@@ -0,0 +1,31 @@
+'use strict';
+
+const common = require('../common.js');
+
+const bench = common.createBenchmark(main, {
+  type: ['Uint8Array', 'Uint16Array', 'Uint32Array', 'Float64Array'],
+  len: [64, 256, 2048],
+  partial: ['none', 'offset', 'offset-length'],
+  n: [6e5],
+});
+
+function main({ n, len, type, partial }) {
+  const TypedArrayCtor = globalThis[type];
+  const src = new TypedArrayCtor(len);
+  for (let i = 0; i < len; i++) src[i] = i;
+
+  let offset;
+  let length;
+  if (partial === 'offset') {
+    offset = len >>> 2;
+  } else if (partial === 'offset-length') {
+    offset = len >>> 2;
+    length = len >>> 1;
+  }
+
+  bench.start();
+  for (let i = 0; i < n; i++) {
+    Buffer.copyBytesFrom(src, offset, length);
+  }
+  bench.end(n);
+}
diff --git a/benchmark/buffers/buffer-fill.js b/benchmark/buffers/buffer-fill.js
@@ -10,6 +10,7 @@ const bench = common.createBenchmark(main, {
     'fill("t")',
     'fill("test")',
     'fill("t", "utf8")',
+    'fill("t", "ascii")',
     'fill("t", 0, "utf8")',
     'fill("t", 0)',
     'fill(Buffer.alloc(1), 0)',

diff --git a/benchmark/buffers/buffer-indexof.js b/benchmark/buffers/buffer-indexof.js
@@ -19,7 +19,7 @@ const searchStrings = [
 
 const bench = common.createBenchmark(main, {
   search: searchStrings,
-  encoding: ['undefined', 'utf8', 'ucs2', 'latin1'],
+  encoding: ['undefined', 'utf8', 'ascii', 'latin1', 'ucs2'],
   type: ['buffer', 'string'],
   n: [5e4],
 }, {

diff --git a/benchmark/buffers/buffer-tostring.js b/benchmark/buffers/buffer-tostring.js
@@ -3,7 +3,7 @@
 const common = require('../common.js');
 
 const bench = common.createBenchmark(main, {
-  encoding: ['', 'utf8', 'ascii', 'latin1', 'hex', 'UCS-2'],
+  encoding: ['', 'utf8', 'ascii', 'latin1', 'hex', 'base64', 'base64url', 'UCS-2'],
   args: [0, 1, 3],
   len: [1, 64, 1024],
   n: [1e6],

diff --git a/lib/buffer.js b/lib/buffer.js
@@ -50,7 +50,6 @@ const {
   TypedArrayPrototypeGetByteOffset,
   TypedArrayPrototypeGetLength,
   TypedArrayPrototypeSet,
-  TypedArrayPrototypeSlice,
   TypedArrayPrototypeSubarray,
   Uint8Array,
 } = primordials;
@@ -383,28 +382,33 @@ Buffer.copyBytesFrom = function copyBytesFrom(view, offset, length) {
     return new FastBuffer();
   }
 
-  if (offset !== undefined || length !== undefined) {
-    if (offset !== undefined) {
-      validateInteger(offset, 'offset', 0);
-      if (offset >= viewLength) return new FastBuffer();
-    } else {
-      offset = 0;
-    }
-    let end;
-    if (length !== undefined) {
-      validateInteger(length, 'length', 0);
-      end = offset + length;
-    } else {
-      end = viewLength;
-    }
+  let start = 0;
+  let end = viewLength;
 
-    view = TypedArrayPrototypeSlice(view, offset, end);
+  if (offset !== undefined) {
+    validateInteger(offset, 'offset', 0);
+    if (offset >= viewLength) return new FastBuffer();
+    start = offset;
   }
 
+  if (length !== undefined) {
+    validateInteger(length, 'length', 0);
+    // The old code used TypedArrayPrototypeSlice which clamps internally.
+    end = MathMin(start + length, viewLength);
+  }
+
+  if (end <= start) return new FastBuffer();
+
+  const viewByteLength = TypedArrayPrototypeGetByteLength(view);
+  const elementSize = viewByteLength / viewLength;
+  const srcByteOffset = TypedArrayPrototypeGetByteOffset(view) +
+                        start * elementSize;
+  const srcByteLength = (end - start) * elementSize;
+
   return fromArrayLike(new Uint8Array(
     TypedArrayPrototypeGetBuffer(view),
-    TypedArrayPrototypeGetByteOffset(view),
-    TypedArrayPrototypeGetByteLength(view)));
+    srcByteOffset,
+    srcByteLength));
 };
 
 // Identical to the built-in %TypedArray%.of(), but avoids using the deprecated
@@ -551,14 +555,15 @@ function fromArrayBuffer(obj, byteOffset, length) {
 }
 
 function fromArrayLike(obj) {
-  if (obj.length <= 0)
+  const { length } = obj;
+  if (length <= 0)
     return new FastBuffer();
-  if (obj.length < (Buffer.poolSize >>> 1)) {
-    if (obj.length > (poolSize - poolOffset))
+  if (length < (Buffer.poolSize >>> 1)) {
+    if (length > (poolSize - poolOffset))
       createPool();
-    const b = new FastBuffer(allocPool, poolOffset, obj.length);
+    const b = new FastBuffer(allocPool, poolOffset, length);
     TypedArrayPrototypeSet(b, obj, 0);
-    poolOffset += obj.length;
+    poolOffset += length;
     alignPool();
     return b;
   }
@@ -732,11 +737,7 @@ const encodingOps = {
     write: asciiWrite,
     slice: asciiSlice,
     indexOf: (buf, val, byteOffset, dir) =>
-      indexOfBuffer(buf,
-                    fromStringFast(val, encodingOps.ascii),
-                    byteOffset,
-                    encodingsMap.ascii,
-                    dir),
+      indexOfString(buf, val, byteOffset, encodingsMap.ascii, dir),
   },
   base64: {
     encoding: 'base64',
@@ -897,17 +898,17 @@ Buffer.prototype.toString = function toString(encoding, start, end) {
     return utf8Slice(this, 0, this.length);
   }
 
-  const len = this.length;
+  const bufferLength = TypedArrayPrototypeGetLength(this);
 
   if (start <= 0)
     start = 0;
-  else if (start >= len)
+  else if (start >= bufferLength)
     return '';
   else
     start = MathTrunc(start) || 0;
 
-  if (end === undefined || end > len)
-    end = len;
+  if (end === undefined || end > bufferLength)
+    end = bufferLength;
   else
     end = MathTrunc(end) || 0;
 
@@ -1118,7 +1119,9 @@ function _fill(buf, value, offset, end, encoding) {
       value = 0;
     } else if (value.length === 1) {
       // Fast path: If `value` fits into a single byte, use that numeric value.
-      if (normalizedEncoding === 'utf8') {
+      // ASCII shares this branch with utf8 since code < 128 covers the full
+      // ASCII range; anything outside falls through to C++ bindingFill.
+      if (normalizedEncoding === 'utf8' || normalizedEncoding === 'ascii') {
         const code = StringPrototypeCharCodeAt(value, 0);
         if (code < 128) {
           value = code;
@@ -1168,29 +1171,30 @@ function _fill(buf, value, offset, end, encoding) {
 }
 
 Buffer.prototype.write = function write(string, offset, length, encoding) {
+  const bufferLength = TypedArrayPrototypeGetLength(this);
   // Buffer#write(string);
   if (offset === undefined) {
-    return utf8Write(this, string, 0, this.length);
+    return utf8Write(this, string, 0, bufferLength);
   }
   // Buffer#write(string, encoding)
   if (length === undefined && typeof offset === 'string') {
     encoding = offset;
-    length = this.length;
+    length = bufferLength;
     offset = 0;
 
   // Buffer#write(string, offset[, length][, encoding])
   } else {
-    validateOffset(offset, 'offset', 0, this.length);
+    validateOffset(offset, 'offset', 0, bufferLength);
 
-    const remaining = this.length - offset;
+    const remaining = bufferLength - offset;
 
     if (length === undefined) {
       length = remaining;
     } else if (typeof length === 'string') {
       encoding = length;
       length = remaining;
     } else {
-      validateOffset(length, 'length', 0, this.length);
+      validateOffset(length, 'length', 0, bufferLength);
       if (length > remaining)
         length = remaining;
     }
@@ -1208,9 +1212,10 @@ Buffer.prototype.write = function write(string, offset, length, encoding) {
 };
 
 Buffer.prototype.toJSON = function toJSON() {
-  if (this.length > 0) {
-    const data = new Array(this.length);
-    for (let i = 0; i < this.length; ++i)
+  const bufferLength = TypedArrayPrototypeGetLength(this);
+  if (bufferLength > 0) {
+    const data = new Array(bufferLength);
+    for (let i = 0; i < bufferLength; ++i)
       data[i] = this[i];
     return { type: 'Buffer', data };
   }
@@ -1235,7 +1240,7 @@ function adjustOffset(offset, length) {
 }
 
 Buffer.prototype.subarray = function subarray(start, end) {
-  const srcLength = this.length;
+  const srcLength = TypedArrayPrototypeGetLength(this);
   start = adjustOffset(start, srcLength);
   end = end !== undefined ? adjustOffset(end, srcLength) : srcLength;
   const newLength = end > start ? end - start : 0;
@@ -1253,45 +1258,52 @@ function swap(b, n, m) {
 }
 
 Buffer.prototype.swap16 = function swap16() {
-  // For Buffer.length < 128, it's generally faster to
+  // Ref: https://github.com/nodejs/node/pull/61871#discussion_r2889557696
+  // For Buffer.length <= 32, it's generally faster to
   // do the swap in javascript. For larger buffers,
   // dropping down to the native code is faster.
-  const len = this.length;
+  const len = TypedArrayPrototypeGetLength(this);
   if (len % 2 !== 0)
     throw new ERR_INVALID_BUFFER_SIZE('16-bits');
-  if (len < 128) {
+  if (len <= 32) {
     for (let i = 0; i < len; i += 2)
       swap(this, i, i + 1);
     return this;
   }
-  return _swap16(this);
+  _swap16(this);
+  return this;
 };
 
 Buffer.prototype.swap32 = function swap32() {
-  // For Buffer.length < 192, it's generally faster to
+  // Ref: https://github.com/nodejs/node/pull/61871#discussion_r2889557696
+  // For Buffer.length <= 32, it's generally faster to
   // do the swap in javascript. For larger buffers,
   // dropping down to the native code is faster.
-  const len = this.length;
+  const len = TypedArrayPrototypeGetLength(this);
   if (len % 4 !== 0)
     throw new ERR_INVALID_BUFFER_SIZE('32-bits');
-  if (len < 192) {
+  if (len <= 32) {
     for (let i = 0; i < len; i += 4) {
       swap(this, i, i + 3);
       swap(this, i + 1, i + 2);
     }
     return this;
   }
-  return _swap32(this);
+  _swap32(this);
+  return this;
 };
 
 Buffer.prototype.swap64 = function swap64() {
-  // For Buffer.length < 192, it's generally faster to
+  // Ref: https://github.com/nodejs/node/pull/61871#discussion_r2889557696
+  // For Buffer.length < 48, it's generally faster to
   // do the swap in javascript. For larger buffers,
   // dropping down to the native code is faster.
-  const len = this.length;
+  // Threshold differs from swap16/swap32 (<=32) because swap64's
+  // crossover is between 40 and 48 (native wins at 48, loses at 40).
+  const len = TypedArrayPrototypeGetLength(this);
   if (len % 8 !== 0)
     throw new ERR_INVALID_BUFFER_SIZE('64-bits');
-  if (len < 192) {
+  if (len < 48) {
     for (let i = 0; i < len; i += 8) {
       swap(this, i, i + 7);
       swap(this, i + 1, i + 6);
@@ -1300,7 +1312,8 @@ Buffer.prototype.swap64 = function swap64() {
     }
     return this;
   }
-  return _swap64(this);
+  _swap64(this);
+  return this;
 };
 
 Buffer.prototype.toLocaleString = Buffer.prototype.toString;