198674 2019-06-07 13:09:51 -0700 Can't extend host objects like URLSearchParameters using JS classes 2020-04-17 15:00:12 -0700 1 1 1 Unclassified WebKit WebCore JavaScript Safari 12 Mac macOS 10.14 RESOLVED CONFIGURATION CHANGED https://bugs.webkit.org/show_bug.cgi?id=174313 InRadar P2 Normal --- 1 webrealizer webkit-unassigned 709922234 achristensen ashvayka fpizlo keith_miller webkit-bug-importer ysuzuki oldest_to_newest 1542914 0 webrealizer 2019-06-07 13:09:51 -0700 This is something that works in other browsers like Chrome but fails in Safari. Try executing code like this class MyParams extends URLSearchParams { constructor(init) { super(init) } test() { alert(1); } } var s1 = new MyParams(); s1.test(); // Works in Chrome but breaks in Safari. I understand that extending host object might be just prohibited but it is hard to find any docs on that or confirmation. Could you clarify what is going on here and why WebKit team decided to block something useful like this. 1543043 1 webkit-bug-importer 2019-06-07 19:02:49 -0700 <rdar://problem/51543664> 1642856 2 ashvayka 2020-04-17 15:00:12 -0700 (In reply to Mikhail V from comment #0) > s1.test(); // Works in Chrome but breaks in Safari. As of r256716, extending URLSearchParams (as well as other DOM constructors) works as expected.