The handler.enumerate() method used to be a trap for for...in statements, but has been removed from the ECMAScript standard in edition 7 and is deprecated in browsers.
The static Reflect.enumerate() method used to return an iterator with the enumerable own and inherited properties of the target object, but has been removed from the ECMAScript standard in edition 7 and is deprecated in browsers.
The static String.raw() method is a tag function of template literals, similar to the r prefix in Python or the @ prefix in C# for string literals (yet there is a difference: see explanations in this issue). It's used to get the raw string form of template strings (that is, the original, uninterpreted text).
The Symbol.hasInstance well-known symbol is used to determine if a constructor object recognizes an object as its instance. The instanceof operator behavior can be customized by this symbol.