[Webkit-unassigned] [Bug 181011] New: JavaScript subclasses of typed arrays produce incorrect type when .of() is called
bugzilla-daemon at webkit.org
bugzilla-daemon at webkit.org
Tue Dec 19 16:40:56 PST 2017
https://bugs.webkit.org/show_bug.cgi?id=181011
Bug ID: 181011
Summary: JavaScript subclasses of typed arrays produce
incorrect type when .of() is called
Product: WebKit
Version: Safari 11
Hardware: iPhone / iPad
OS: iOS 11
Status: NEW
Severity: Normal
Priority: P2
Component: JavaScriptCore
Assignee: webkit-unassigned at lists.webkit.org
Reporter: garett.ridge at gmail.com
I show a very small demo of this bug here:
https://jsfiddle.net/dumb_lowtax/4pfn6e6L/
The short snippet there outputs a different result on iPhones and iPads than everywhere else. It tries subclassing Float32Array and adding to it a method called "times()" for multiplying by a scalar. This custom method comes up as undefined when using iOS. In practice this means that my WebGL game engine works on all platforms except Apple, where all the basic vector types don't work.
The snippet helpfully logs the result of "v instanceof Vec" where Vec extends a typed array and v was created with .of(). That too shows different results only on those devices, exposing the root problem. The built in of() functionality is returning type Float32Array instead of Vec. Hovering over the variable in Web Inspector corroborates this.
Weirdness that I've experienced in the past with subclassing the typed arrays and getting unexpected behavior is already the reason I'm having to use "Vec.of( 1,2,3 )" everywhere, instead of just saying "new Vec( 1,2,3 )".
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