JavaScript: Avoid referring to arguments

[seanpdoyle]

Avoid using arguments unnecessarily.

Inspired by petkaantonov/bluebird's "Optimization Killers"
wiki.

Using arguments without .length or [i] makes it nearly impossible
for V8 to optimize the function block.

[BlakeWilliams]

👍

[joshuaclayton]

👍

[drapergeek]

👍

[mcmire]

Yup, makes sense. (And you don't need this anymore with the argument spread syntax.)

[seanpdoyle]

@mcmire avoiding ...arguments is what this is addressing

[mcmire]

Oh, I thought this was addressing avoiding referring to arguments, which is a "special variable" automatically available inside any function.

AFAIK, the spread syntax actually creates a new variable that is non-special. (You could write ...arguments or ...args or ...whatever, in other words.) Or I am off-base on that?

[seanpdoyle]

@mcmire I'm not sure. @BlakeWilliams made that comment that inspired this PR, so maybe he know for certain.

[BlakeWilliams]

This example shows that it's still using arguments directly.

[mcmire]

Ah, good to know, thanks.

It seems like the following syntax is prohibited in strict mode, as well:

function foo(...arguments) {
  // ...
}

However, you can say this:

function foo(...args) {
  // ...
}

So, do you think that this is useful to distinguish? i.e. something like "As an alternative to arguments, use the spread syntax with a variable that is not arguments."

[BlakeWilliams]

I think it's worth mentioning an alternative any time we recommend against something. 👍 to ...args

[seanpdoyle]

@mcmire @BlakeWilliams I've pushed an update with a sample.

[mcmire]

Sweet, looks good!

[BlakeWilliams]

Looks great!

[seanpdoyle]

During this deep dive into Ember.View, @rwjblue replaces this._super.apply(this, arguments) with this._super(...arguments).

EDITED

[rwjblue]

Technically, I replaced this._super.apply(this, arguments) with this._super(...arguments). The later transpiles to the former (as pointed out earlier in the thread above).

Also, the article referenced specifically states that calling fn.apply is a special exemption from the deopts associated with the arguments object.

[seanpdoyle]

@BlakeWilliams from the wiki:

STRICTLY fn.apply(y, arguments) is ok, nothing else is, e.g. .slice. Function#apply is special.

From your example:

_get(Object.getPrototypeOf(Bar.prototype), "constructor", this).apply(this, arguments);

[seanpdoyle]

Given this new information, I'm closing this PR.