Make call to super() implicit within constructor

[nippur72]

Calling super() within a constructor is a bit redundant and annoying... can we have it called implicitly if call to super is omitted?

For example this

class Manager extends Employee {
   constructor() {
      this.title = "The Manager";
   }
}

should be equivalent to

class Manager extends Employee {
   constructor() {
      super(); // call to default constructor added implicitly      
      this.title = "The Manager";
   }
}

(C# also does a similar thing and it's a nice feature).

[coreh]

What would be the default behavior for the parameters? Would they be passed on to the super class constructor if the signature was the same?

[nippur72]

@coreh that would be a possibility, since you can always override it by making an explicit call to super(). It would do no harm to existing code.

[GoToLoop]

Gonna add that like C#, Java does the same too for empty super constructors! :D

[mhegazy]

TypeScript is and should be a super set of JavaScript ES6 semantics has no implicit call for constructors, if TS supports that, a TS/ES6 class are not identical in behavior.

[GoToLoop]

As long as some handy feature isn't detrimental to ES6 compatibilty, I don't see why it should be thrown away.
This proposal merely asks for TS' compiler to match some of the smartness of C# & Java compilers.
It won't affect codes which don't use this saving grace feature.

Since TS is a compiler/transpiler it can do tricks that raw JS can't after all.
Many C# & Java programmers would be attracted to JS world if TS would mirror many of C#/Java features where it's feasible to do so.

[nippur72]

peraphs there could be a compiler flag like #274 to turn on and off features like this one.

[ghost]

What if my intention was to call super() after the this.title assignment in certain use-case.
We cannot generalize when the user wants to call super() ctor, therefore this seems like bit over-engineering TBH.

[nippur72]

@jasonwilliams200OK the new behaviour would be:

• if there's no super() call and the class has a default constructor, instead of throwing an error, make a call to super() as the first thing in the constructor.
• else work as before

Your special case would be covered by calling super explicitly. (And btw, is it possible to refer to this before super?)

[RyanCavanaugh]

What if my intention was to call super() after the this.title assignment in certain use-case.

Note that this is disallowed in ES6. You cannot access this until after the super call.

[ghost]

@RyanCavanaugh, thanks, this. was indeed a bad example. The point was to retain user in control to defer super() call as first thing in the ctor.

[mhegazy]

As mentioned above, we would like to keep the semantics matching JS, and issue warnings to help guide the user the correct behavior.