Opera, Inevitably Unexpected
Update Opera fellas works at speed light, the problem described in this post has been patched already , great stuff and thanks! Just a quick one, about what I have discovered with Opera 10.62 when I have tested wru against this browser ... // host object var xhr = new XMLHttpRequest; // this is true alert("addEventListener" in xhr); // this is undefined // not even null // simply undefined!!! alert(xhr.addEventListener); The Problem 99% of libraries out there are assuming that key in object is one of the fastest and most reliable way to have features detection . Today, we know that this assumption is wrong . It's not about the reproducibility of the problem: var o = {}; o.key = o.key; "key" in o && o.key; It's about an ... Epic Fail (Already Fixed!) The engine " behind the scene " is broken . Whatever it happens there, we have a broken chain through pseudo inheritance that exposes publicly a method that does not exist , which brings u...