Javascript DataView Type

Introduction

DataView is a type of view that can read and write an ArrayBuffer.

DataView does not assume anything about the buffer contents.

DataView is not iterable.

A DataView must be created to read from and write to an ArrayBuffer that already exists.

It can use the whole buffer or only part of it.

DataView maintains a reference to the buffer instance. 

const buf = new ArrayBuffer(16);//from w w  w  .  j a  v  a  2 s . c  om

// DataView default to use the entire ArrayBuffer 
const fullDataView = new DataView(buf);
console.log(fullDataView.byteOffset); // 0 
console.log(fullDataView.byteLength); // 16 
console.log(fullDataView.buffer === buf); // true

Constructor takes an optional byte offset and byte length

byteOffset=0 begins the view at the start of the buffer

byteLength=8 restricts the view to the first 8 bytes 

const buf = new ArrayBuffer(16);/*from w  ww  . j av  a 2  s . c  o m*/
const firstHalfDataView = new DataView(buf, 0, 8);
console.log(firstHalfDataView.byteOffset); // 0 
console.log(firstHalfDataView.byteLength); // 8 
console.log(firstHalfDataView.buffer === buf); // true

DataView will use the remainder of the buffer unless specified

byteOffset=8 begins the view at the 9th byte of the buffer.

byteLength default is the remainder of the buffer 

const buf = new ArrayBuffer(16);//w w  w  .  j  a v a2  s  .  c  om
const secondHalfDataView = new DataView(buf, 8);
console.log(secondHalfDataView.byteOffset); // 8 
console.log(secondHalfDataView.byteLength); // 8 
console.log(secondHalfDataView.buffer === buf); // true



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