Functions - Arguments Object

[Si Robertson]

From the proposal ...

  It is a (early) ReferenceError to refer to the implicit 'arguments' variable

  inside a 'function' expression or declaration.

How do we create proxy functions to change the execution context of event listeners etc in strong mode?

  function proxy(context, func) {

    let n = func.length;

    if (n === 0) {

      return function() {

        return func.call(context);

      }

    }

    if (n === 1) {

      return function(a) {

        return func.call(context, a);

      }

    }

    ...

    return function() {

      return func.apply(context, arguments); // error?

    }

  }

I'm aware of Object.bind() but custom functions are typically optimal and obviously customizable.

[Sébastien Doeraene]

Hi,

You can use a rest parameter for this purpose:

return function(...args) {
  return func.apply(context, args);
}

In general, rest parameters supersede usages of arguments when it comes to dealing with varargs. Even in regular ES6.

Also, consider using arrow functions in the first place instead, which keep the `this` from the enclosing method/function.

Cheers,
Sébastien

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[Si Robertson]

Thanks, Sébastien

Using the rest parameter makes sense, hopefully V8 will support that feature soon.

[Sébastien Doeraene]

Hi,

V8 already supports rest parameters, but you need to enable them with --harmony-rest-parameters. At least that works for me with a d8 I built around a week ago.

Sébastien

[Dmitry Lomov]

On Tue, Mar 17, 2015 at 10:04 AM, Sébastien Doeraene <sjrdo...@gmail.com> wrote:

Hi,

V8 already supports rest parameters, but you need to enable them with --harmony-rest-parameters. At least that works for me with a d8 I built around a week ago.

Just to clarify, rest parameters are work-in-progress for now (although we actively working on them) - do not use in production :)

To view this discussion on the web, visit https://groups.google.com/d/msgid/strengthen-js/CAJwkOg6o4F_%2Bw6Tut56tCSxWM-hNrkmjqZrYg7aqxUn0wCjWbQ%40mail.gmail.com.