Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

buffer: make byteLength work with ArrayBuffer & DataView #5255

Closed
wants to merge 1 commit into from
Closed

buffer: make byteLength work with ArrayBuffer & DataView #5255

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 8 additions & 1 deletion doc/api/buffer.markdown
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -468,7 +468,7 @@ additional performance that `Buffer.allocUnsafe(size)` provides.

### Class Method: Buffer.byteLength(string[, encoding])

* `string` {String}
* `string` {String | Buffer | TypedArray | DataView | ArrayBuffer}
* `encoding` {String} Default: `'utf8'`
* Return: {Number}

Expand All @@ -487,6 +487,11 @@ console.log(`${str}: ${str.length} characters, ` +
// ½ + ¼ = ¾: 9 characters, 12 bytes
```

When `string` is a `Buffer`/[`DataView`][]/[`TypedArray`][]/`ArrayBuffer`,
returns the actual byte length.

Otherwise, converts to `String` and returns the byte length of string.

### Class Method: Buffer.compare(buf1, buf2)

* `buf1` {Buffer}
Expand Down Expand Up @@ -1727,3 +1732,5 @@ console.log(buf);
[buffer_allocunsafe]: #buffer_class_method_buffer_allocraw_size
[buffer_alloc]: #buffer_class_method_buffer_alloc_size_fill_encoding
[`TypedArray.from()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/from
[`DataView`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView
[`TypedArray`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray
7 changes: 4 additions & 3 deletions lib/buffer.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -317,11 +317,12 @@ function base64ByteLength(str, bytes) {


function byteLength(string, encoding) {
if (string instanceof Buffer)
return string.length;
if (typeof string !== 'string') {
if (ArrayBuffer.isView(string) || string instanceof ArrayBuffer)
return string.byteLength;

if (typeof string !== 'string')
string = '' + string;
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

nit: string += '' works too

}

var len = string.length;
if (len === 0)
Expand Down
34 changes: 34 additions & 0 deletions test/parallel/test-buffer-bytelength.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3,19 +3,53 @@
require('../common');
var assert = require('assert');
var Buffer = require('buffer').Buffer;
var SlowBuffer = require('buffer').SlowBuffer;

// coerce values to string
assert.equal(Buffer.byteLength(32, 'binary'), 2);
assert.equal(Buffer.byteLength(NaN, 'utf8'), 3);
assert.equal(Buffer.byteLength({}, 'binary'), 15);
assert.equal(Buffer.byteLength(), 9);

var buff = new Buffer(10);
assert(ArrayBuffer.isView(buff));
var slowbuff = new SlowBuffer(10);
assert(ArrayBuffer.isView(slowbuff));

// buffer
var incomplete = Buffer.from([0xe4, 0xb8, 0xad, 0xe6, 0x96]);
assert.equal(Buffer.byteLength(incomplete), 5);
var ascii = Buffer.from('abc');
assert.equal(Buffer.byteLength(ascii), 3);

// ArrayBuffer
var buffer = new ArrayBuffer(8);
assert.equal(Buffer.byteLength(buffer), 8);

// TypedArray
var int8 = new Int8Array(8);
assert.equal(Buffer.byteLength(int8), 8);
var uint8 = new Uint8Array(8);
assert.equal(Buffer.byteLength(uint8), 8);
var uintc8 = new Uint8ClampedArray(2);
assert.equal(Buffer.byteLength(uintc8), 2);
var int16 = new Int16Array(8);
assert.equal(Buffer.byteLength(int16), 16);
var uint16 = new Uint16Array(8);
assert.equal(Buffer.byteLength(uint16), 16);
var int32 = new Int32Array(8);
assert.equal(Buffer.byteLength(int32), 32);
var uint32 = new Uint32Array(8);
assert.equal(Buffer.byteLength(uint32), 32);
var float32 = new Float32Array(8);
assert.equal(Buffer.byteLength(float32), 32);
var float64 = new Float64Array(8);
assert.equal(Buffer.byteLength(float64), 64);

// DataView
var dv = new DataView(new ArrayBuffer(2));
assert.equal(Buffer.byteLength(dv), 2);

// special case: zero length string
assert.equal(Buffer.byteLength('', 'ascii'), 0);
assert.equal(Buffer.byteLength('', 'HeX'), 0);
Expand Down