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buffer: make byteLength work with ArrayBuffer & DataView · nodejs/node@ee83c95 · GitHub

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Commit ee83c95

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JacksonTian
authored and
evanlucas
committed
buffer: make byteLength work with ArrayBuffer & DataView
Convert anything to string, but Buffer, TypedArray and ArrayBuffer ``` var uint8 = new Uint8Array([0xf0, 0x9f, 0x90]); Buffer.byteLength(uint8); // should be 3, but returns 11 Buffer.byteLength(uint8.buffer); // should be 3, but return 20 ``` PR-URL: #5255 Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl> Reviewed-By: Trevor Norris <trev.norris@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com>
1 parent 1f8e4b5 commit ee83c95

3 files changed

Lines changed: 47 additions & 5 deletions

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‎doc/api/buffer.markdown‎

Lines changed: 9 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -451,7 +451,7 @@ additional performance that `Buffer.allocUnsafe(size)` provides.
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### Class Method: Buffer.byteLength(string[, encoding])
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* `string` {String}
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* `string` {String | Buffer | TypedArray | DataView | ArrayBuffer}
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* `encoding` {String} Default: `'utf8'`
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* Return: {Number}
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@@ -470,6 +470,11 @@ console.log(`${str}: ${str.length} characters, ` +
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// ½ + ¼ = ¾: 9 characters, 12 bytes
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```
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When `string` is a `Buffer`/[`DataView`][]/[`TypedArray`][]/`ArrayBuffer`,
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returns the actual byte length.
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Otherwise, converts to `String` and returns the byte length of string.
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### Class Method: Buffer.compare(buf1, buf2)
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* `buf1` {Buffer}
@@ -1744,4 +1749,6 @@ console.log(buf);
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[buffer_from_string]: #buffer_class_method_buffer_from_str_encoding
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[buffer_allocunsafe]: #buffer_class_method_buffer_allocraw_size
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[buffer_alloc]: #buffer_class_method_buffer_alloc_size_fill_encoding
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[`TypedArray.from()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/from
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[`TypedArray.from()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/from
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[`DataView`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView
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[`TypedArray`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray

‎lib/buffer.js‎

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -340,11 +340,12 @@ function base64ByteLength(str, bytes) {
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function byteLength(string, encoding) {
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if (string instanceof Buffer)
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return string.length;
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if (typeof string !== 'string') {
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if (ArrayBuffer.isView(string) || string instanceof ArrayBuffer)
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return string.byteLength;
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if (typeof string !== 'string')
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string = '' + string;
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}
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var len = string.length;
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if (len === 0)

‎test/parallel/test-buffer-bytelength.js‎

Lines changed: 34 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -3,19 +3,53 @@
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require('../common');
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var assert = require('assert');
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var Buffer = require('buffer').Buffer;
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var SlowBuffer = require('buffer').SlowBuffer;
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// coerce values to string
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assert.equal(Buffer.byteLength(32, 'binary'), 2);
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assert.equal(Buffer.byteLength(NaN, 'utf8'), 3);
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assert.equal(Buffer.byteLength({}, 'binary'), 15);
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assert.equal(Buffer.byteLength(), 9);
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var buff = new Buffer(10);
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assert(ArrayBuffer.isView(buff));
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var slowbuff = new SlowBuffer(10);
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assert(ArrayBuffer.isView(slowbuff));
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// buffer
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var incomplete = new Buffer([0xe4, 0xb8, 0xad, 0xe6, 0x96]);
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assert.equal(Buffer.byteLength(incomplete), 5);
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var ascii = new Buffer('abc');
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assert.equal(Buffer.byteLength(ascii), 3);
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// ArrayBuffer
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var buffer = new ArrayBuffer(8);
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assert.equal(Buffer.byteLength(buffer), 8);
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// TypedArray
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var int8 = new Int8Array(8);
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assert.equal(Buffer.byteLength(int8), 8);
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var uint8 = new Uint8Array(8);
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assert.equal(Buffer.byteLength(uint8), 8);
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var uintc8 = new Uint8ClampedArray(2);
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assert.equal(Buffer.byteLength(uintc8), 2);
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var int16 = new Int16Array(8);
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assert.equal(Buffer.byteLength(int16), 16);
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var uint16 = new Uint16Array(8);
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assert.equal(Buffer.byteLength(uint16), 16);
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var int32 = new Int32Array(8);
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assert.equal(Buffer.byteLength(int32), 32);
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var uint32 = new Uint32Array(8);
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assert.equal(Buffer.byteLength(uint32), 32);
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var float32 = new Float32Array(8);
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assert.equal(Buffer.byteLength(float32), 32);
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var float64 = new Float64Array(8);
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assert.equal(Buffer.byteLength(float64), 64);
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// DataView
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var dv = new DataView(new ArrayBuffer(2));
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assert.equal(Buffer.byteLength(dv), 2);
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// special case: zero length string
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assert.equal(Buffer.byteLength('', 'ascii'), 0);
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assert.equal(Buffer.byteLength('', 'HeX'), 0);

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