Not today, but last night, I was made aware of the fact that JavaScriptCore, which is the JavaScript engine made and used by Apple in their browsers does Date parsing from string a little differently from SpiderMonkey (Mozilla) and V8 (Google). In particular, on SpiderMonkey and V8,

new Date("1950-1-1") // returns Date Sun Jan 01 1950 07:30:00 GMT+0...

which is a proper Date object with timezone. On the other hand, on JavaScriptCore

new Date("1950-1-1") // returns Invalid Date