How to check if a variable is a typed array in javascript?

javascript json stringify typedarray
AGD picture AGD · Mar 6, 2013 · Viewed 16.7k times · Source

I'm working on a game and we make extensive use of typed arrays (Float32Arrays) for our math types. We save and load the gamestate from JSON. An example of JSON stringify output is for such an array (in Chrome) is: 

"{"0":0,"1":0,"2":0,"length":3,"byteLength":12,"byteOffset":0,"buffer":{"byteLength":12}}"

This wastes space and causes them to be loaded as objects which is inconvenient. Ideally we could use the stringify 'replacer' function to test if a variable is a typed array, and then convert it to a bog standard array in that case. Unfortunately I'm not sure how to reliably test whether a variable is a typed array or not.

Any help?

Answer

Greg Tatum picture Greg Tatum · Apr 15, 2015

ArrayBuffer.isView should help you out.

var data = [0,1,2]
var dataBuffer = new ArrayBuffer( data )
var dataBufferView = new Float32Array( data )

ArrayBuffer.isView(data) //false
ArrayBuffer.isView(dataBuffer) //false
ArrayBuffer.isView(dataBufferView) //true
dataBuffer instanceof ArrayBuffer //true

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