Allow this inside the body if no explicit name provided

[hax]

Update: function(this) {} already be supported by TS from 2016, also supported by Closure compiler (search "function this type"), and also have PR in Flowtype.

Original comment:

This is the example of current proposal:

function method (this elem, e) {
  console.log("Elem:", elem) // OK
  console.log("this:", this) // <-- Throws an error!
}

I suggest allow this inside the body if no explicit name provided, so we can write:

function method (this, e) {
  console.log("this:", this) // <-- That's ok
}

Though it looks redundant, it will be useful for type annotation (See microsoft/TypeScript#6739 and facebook/flow#452 (comment)), and linter (See http://eslint.org/docs/rules/no-invalid-this and http://eslint.org/docs/rules/prefer-arrow-callback#allowunboundthis).

---

Update: I changed my mind that this part should be leave to linters.

Original comments:

And current proposal allow this in inner functions:

runTask(function cb (this elem, e) {

  elem.runAsyncTask(function () {
    console.log("Outer elem:", elem) // OK
    console.log("Inner this:", this) // OK
  });
})

I suggest do not allow it, but require adding this in the arguments:

runTask(function cb (this elem, e) {

  elem.runAsyncTask(function () {
    console.log("Outer elem:", elem) // OK
    console.log("Inner this:", this) // Syntax error
  });
  elem.runAsyncTask(function (this) {
    console.log("Outer elem:", elem) // OK
    console.log("Inner this:", this) // OK
  });
})

[gilbert]

Allowing for no explicit name seems good to me.

Wouldn't making it required break backwards compatibility?

[hax]

As I understand, it won't break backwards compatibility. this in parameter position is syntax error now. For example new Function('this', '') throw SyntaxError.