Make Rtrace ESM by default, with UMD fallback

[dcodeIO]

Does what #1513 did for the loader for RTrace as well.

• I've read the contributing guidelines

[MaxGraey]

How about use arrow functions instead bindings?
instead this.load_val_i32 = this.load_val_i32.bind(this) just use later:

load_val_i32 = (id, value) => {
   return value;
}

and for rest methods use the same.

[dcodeIO]

Do you mean moving all of the declarations into the ctor like that?

[MaxGraey]

No, just remove this.load_val_i32 = this.load_val_i32.bind(this) and friends and bind this via arrow function during declaration like:

class RTrace {

   ....
  onresize = () => { 
      ...
  }
  load_val_i32 = (id, value) => {
     return value;
  }
  ....
}

instead:

class RTrace {
   constructor() {
       this.onresize = this.onresize.bind(this);
       this.load_val_i32 = this.load_val_i32.bind(this);
   }
   ....
   onresize() {
       ....
   }
   load_val_i32(id, value) {
     return value;
  }
}

[dcodeIO]

Hmm, how would that look for

  load_ptr(id, bytes, offset, address) {
    this.accessShadow(address + offset, bytes, true);
    return address;
  }

when this is accessed?

[dcodeIO]

Also note that binding the functions makes them usable without a proper this context, i.e. as a Wasm import that naturally loses the this context. Wondering if that'd still work when not binding.

[MaxGraey]

instance methods defined via arrow function grabbed current context (this of class or object). It's typical alternative for this.method = this.method.bind(this)

[dcodeIO]

Hmm

SyntaxError: unknown: Support for the experimental syntax 'classProperties' isn't currently enabled (179:11):

  177 |   // Runtime instrumentation
  178 |
> 179 |   onalloc = (ptr) => {

[MaxGraey]

Hmm, class properties should work since V8 7.2 or even earlier

[dcodeIO]

Yeah, I think that's a Babel-ish error. May I suggest to make this a follow-up? Otherwise sounds good if it works!

[MaxGraey]

For babel you should just add this: https://babeljs.io/docs/en/babel-plugin-syntax-class-properties. It add only syntax for parser, but don't do actually transformation (lowering)