allow use before define

[turadg]

no ticket

Description

The no-use-before-define rule was motivated by when variables could hoist up in surprising ways. We always use let and const which have the Temporal Dead Zone that will throw an error if used before declaration.

So we don't need this rule anymore and it's mostly noise.

This also removes no-constant-condition.

Whenever someone wants the rule they can still opt in,

/* eslint no-use-before-define: "error" */

Security Considerations

n/a, lint

Scaling Considerations

n/a, lint

Documentation Considerations

reduces need for docs

Testing Considerations

CI

Upgrade Considerations

n/a, lint

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View logs

[dckc]

... We always use let and const

We haven't removed all use of function. It looks like hundreds of them remain.

https://github.com/Agoric/agoric-sdk/blob/master/packages/SwingSet/src/controller/controller.js
https://github.com/Agoric/agoric-sdk/blob/master/packages/SwingSet/src/kernel/kernel.js

agoric-sdk/packages/vats/src/crc.js

Line 16 in e4a6095

function convert(data) {

etc.

I don't think we even have a lint rule to avoid it.

[turadg]

We haven't removed all use of function. It looks like hundreds of them remain.

Good point. But as you also point out this rule doesn't pertain to those.

Any reason to keep this rule?

[dckc]

We haven't removed all use of function. It looks like hundreds of them remain.

Good point. But as you also point out this rule doesn't pertain to those.

use-before-defined does apply to functions, IIUC.

What I meant was: we don't have a rule to say "use const instead of function".

[kriskowal]

I support this change even if we don’t fully migrate from function to const arrow functions. I happen to write a great deal of mutually recursive code that is best explained in the subjectively wrong order, so that is a bias, and I just don’t experience the surprise of using before definition at runtime in practice. I can’t speak for everyone, though.

[dckc]

Does this mean I can go back to writing code top-down? oh my. whee!

[Chris-Hibbert]

I don't have a problem with these changes to our coding style.

We always use let and const which have the Temporal Dead Zone that will throw an error if used before declaration.

Is use of function rather than let susceptible to the TDZ problem? That seems like an issue.

[erights]

As suggested, #10464 would now globally suppress no-constant-condition, by borrowing that portion of this PR.

[erights]

As agreed verbally. LGTM, thanks!