ArrayBuffer, binary arrays

Web ()

JavaScript

:

• ArrayBuffer, Uint8Array, DataView, Blob, File, etc.

JavaScript

ArrayBuffer

:

let buffer = new ArrayBuffer(16); //  16 
alert(buffer.byteLength); // 16

16

ArrayBuffer

ArrayBuffer (view)

ArrayBuffer

:

• Uint8Array ArrayBuffer 0 255 (18) 8(8-bit unsigned integer)
• Uint16Array 20 65535 16
• Uint32Array 4 0 4294967295 32
• Float64Array 8 5.0x10-324 1.8x10308

16 ArrayBuffer 16 , 8 (2), 4 (4), 2(8

[]

ArrayBuffer

e.g:

let buffer = new ArrayBuffer(16); //  16 

let view = new Uint32Array(buffer); // 32 

alert(Uint32Array.BYTES_PER_ELEMENT); // 4 

alert(view.length); // 4, 
alert(view.byteLength); // 16, 

// 
view[0] = 123456;

// 
for(let num of view) {
  alert(num); // 123456,  0, 0, 0 ( 4 )
}

TypedArray

(Uint8Array, Uint32Array, etc) TypedArray

: (iterable)

(Int8Array Float64Array )

5 :

new TypedArray(buffer, [byteOffset], [length]);
new TypedArray(object);
new TypedArray(typedArray);
new TypedArray(length);
new TypedArray();

1. ArrayBuffer

   byteOffset ( 0)length () buffer

2. Array

   :

   let arr = new Uint8Array([0, 1, 2, 3]);
   alert( arr.length ); // 4
   alert( arr[1] ); // 1

3. TypedArray :

   let arr16 = new Uint16Array([1, 1000]);
   let arr8 = new Uint8Array(arr16);
   alert( arr8[0] ); // 1
   alert( arr8[1] ); // 232 (1000 1000  8 (1000  11 1110 1000, 232  1110 1000)

4. length TypedArray.BYTES_PER_ELEMENT length :

   let arr = new Uint16Array(4); //  4 
   alert( Uint16Array.BYTES_PER_ELEMENT ); //  2 
   alert( arr.byteLength ); // 8 ()

ArrayBuffer TypedArray ArrayBuffer (ArrayBuffer )

ArrayBuffer :

• arr.buffer ArrayBuffer
• arr.byteLength ArrayBuffer

:

let arr8 = new Uint8Array([0, 1, 2, 3]);

// 
let arr16 = new Uint16Array(arr8.buffer);

:

• Uint8Array, Uint16Array, Uint32Array 8, 16, 32
  • Uint8ClampedArray 8 ()
• Int8Array, Int16Array, Int32Array (
• Float32Array, Float64Array 32, 64

256 Uint8Array ()256 100000000 (9)Uint8Array 8 0 255

()8:

[]

257 100000001 (9) 8 1 :

[]

:

let uint8array = new Uint8Array(16);

let num = 256;
alert(num.toString(2)); // 100000000 ()

uint8array[0] = 256;
uint8array[1] = 257;

alert(uint8array[0]); // 0
alert(uint8array[1]); // 1

Uint8ClampedArray 255 255 0

TypedArray

TypedArray Array

map, slice, find, reduce

:

• splice buffer
• concat

2:

• arr.set(fromArr, [offset]) fromArr arr offset ( 0)
• arr.subarray([begin, end]) begin end () slice ()

DataView

DataView ArrayBuffer

• i arr[i]
• DataView .getUint8(i) .getUint16(i)

:

new DataView(buffer, [byteOffset], [byteLength])

• buffer ArrayBuffer DataView buffer
• byteOffset ( 0)
• byteLength ( buffer )

:

let buffer = new Uint8Array([255, 255, 255, 255]).buffer;

let dataView = new DataView(buffer);

//  0 8
alert( dataView.getUint8(0) ); // 255

//  0 16 2
alert( dataView.getUint16(0) ); // 65535 (16)

//  0 32
alert( dataView.getUint32(0) ); // 4294967295 (32)

dataView.setUint32(0, 0); // 4 0 

DataView E.g (1632 float)DataView

ArrayBuffer

ArrayBuffer

• TypedArray:
  • Uint8Array, Uint16Array, Uint32Array 8, 16 32
  • Uint8ClampedArray 8
  • Int8Array, Int16Array, Int32Array ()
  • Float32Array, Float64Array 32, 64
• DataView getUint8(offset).

ArrayBuffer .buffer

2:

• ArrayBufferView
• BufferSource ArrayBuffer ArrayBufferView

BufferSource ArrayBuffer

:

[]