Re: [whatwg] BinaryEncoding for Typed Arrays using window.btoa and window.atob

[Simon Pieters]

On Mon, 05 Aug 2013 16:10:50 +0200, Chang Shu <csh...@gmail.com> wrote:
window.btoa

Summary

Creates a base-64 encoded ASCII string from either a "string" of
binary data or a Typed Array.

Syntax

var encodedData = window.btoa(dataToEncode);

Note that there is no syntax change in window.btoa API.

Example

var encodedData = window.btoa("hello"); //encode a string. Consider
the string as 'binary'

var arr = new Int32Array(3);
arr[0] = 1;
arr[1] = 2;
arr[2] = 3;
var encodedData = window.btoa(arr); //encode integer data into a base-64  
string

window.atob

Summary

Decodes a base-64 encoded ASCII string into a "string" of binary data
and a Typed Array if parameter provided.

Syntax

var decodedArr = new Int32Array();
var decodedData = window.atob(encodedData, [Optinoal] decodedArr);

Note that the 2nd parameter is optional which keeps the backward  
compatibility.

Example

var arr = new Int32Array(3);
arr[0] = 1;
arr[1] = 2;
arr[2] = 3;
var encodedData = window.btoa(arr); //encode integer data into a base-64  
string

var newarr = new Int32Array();
window.atob(encodedData, newarr); //decode base-64 string back to  
integer array
//newarr[0] should be 1, newarr[1] should be 2 and newarr[2] should be 3.

Is there a reason to support an arbitrary typed array for atob rather than  
returning a new typed array?

e.g.

var newarr = atob(encodedData, {typedarray:true});

(I'm not sure which view is most appropriate to return.)

--
Simon Pieters
Opera Software