Dynamic Imports and BigInt have arrived at Stage 4 🎉

[mysticatea]

• tc39/proposals@b04295f
• BigInt to stage 4 tc39/proposals#217 ( Stage 4 acceptance (pending editor signoff on PR) )

Dynamic Imports and BigInt have arrived at Stage 4.
This is the tracking issue to support the new syntaxes.

• add Dynamic Imports and BigInt as ES2020 estree/estree#198 ESTree Spec Update
• Update dynamic imports AST acornjs/acorn#844 Acorn Update
• Update: add ImportExpression eslint-visitor-keys#8 eslint-visitor-keys Update
• Update: support bigint and dynamic import espree#415 espree Update
• ESLint Update 1: the following stuff look like to need update.
  • Update: support bigint and dynamic import (refs #11803) #11983 envs should have new globals (BigInt, BigInt64Array, and BigUint64Array)
  • Update: support bigint and dynamic import (refs #11803) #11983 CodePathAnalyzer: should recognize ImportExpression node as a throwable node.
  • Update: support bigint and dynamic import (refs #11803) #11983 astUtils.getPrecedence(node): should recognize ImportExpression literals.
  • Update: support bigint and dynamic import (refs #11803) #11983 astUtils.isNullLiteral(node): should recognize BigInt literals.
  • Update: support bigint and dynamic import (refs #11803) #11983 func-call-spacing rule: should recognize ImportExpression node. (or new rule?)
  • Update: support bigint and dynamic import (refs #11803) #11983 function-paren-newline rule: should recognize ImportExpression node. (or new rule?)
  • Update: support bigint and dynamic import (refs #11803) #11983 indent rule: should recognize ImportExpression node.
  • Update: support bigint and dynamic import (refs #11803) #11983 new-cap rule: should recognize BigInt function.
  • Update: support bigint and dynamic import (refs #11803) #11983 no-extra-parens rule: should recognize ImportExpression node.
  • Update: support "bigint" in valid-typeof rule #11802 valid-typeof rule: should recognize BigInt type.
• ESLint Update 2: the following stuff look like to need update, but breaking changes.
  • no-compare-neg-zero rule: should recognize BigInt literals.
  • Breaking: some rules recognize bigint literals (fixes #11803) #12701 no-extend-native rule: should recognize BigInt function.
  • Breaking: some rules recognize bigint literals (fixes #11803) #12701 no-magic-number rule: should recognize BigInt literals.
  • Breaking: some rules recognize bigint literals (fixes #11803) #12701 yoda rule: should recognize BigInt literals.

[g-plane]

I have opened an issue at Acorn's repo: acornjs/acorn#833 .

[mercmobily]

While this gets implemented (thank you!), is there a way to get around it with an ignore?
At the moment, if you have:

import(resolvedPageUrl)

you get:

Parsing error: 'import' and 'export' may only appear at the top level

The problem is that this is a parsing error... so the file doesn't get linted at all.
Is there a workaround while we wait for this to actually land? (It looks like it may be a little while!)

[g-plane]

You can use babel-eslint as parser.

[dandv]

You can use babel-eslint as parser.

I'm trying to be babel-free.

Please revisit #11189 as well.

[g-plane]

Don't worry. Dynamic imports will be supported by ESLint itself finally. However, this is still in progress, so you need babel-eslint at present.

[mysticatea]

Yeah, it's working in progress. As the issue description says, we are awaiting ESTree spec to be determined because we cannot implement it until the spec gets stable.

[mdjermanovic]

I guess no-octal doesn't need any changes, apart from a couple of test cases perhaps?

typeof node.value === "number" condition will ignore bigints in all environments.

This rule disallows 017, not 0o17, so 0o17n should be fine.

017n should be already a syntax error,

[mysticatea]

Oh, you are right.

[mysticatea]

We are still awaiting ESTree's decide. I'm wondering that we should fork the AST spec because that PR has been inactive since two months ago.

[mysticatea]

Yay, that PR has been merged!

[mercmobily]

acornjs/acorn#844 has been merged too

[mercmobily]

#11802 has also been merged

[abdonrd]

eslint/eslint-visitor-keys#8 has also been merged!

[NemoStein]

Now that we have estree/estree@9a38106 in ESTree spec, what is the status of this issue?

[platinumazure]

@NemoStein Please look at the task list in the initial post. At this point, we have updated espree and just need to release espree and consume in ESLint, and then we can review and merge PRs like #11983.

I'm hoping we can make big strides in this area for our users with the upcoming ESLint minor release sometime this weekend. But I can't promise anything. 😄

[jesperkristensen]

I noticed today that dynamic imports now works with the latest eslint release, even though this issue has not been updated.

[mercmobily]

Hi, Do they? From master, or npm? Merc.

…

On Sun., 1 Sep. 2019, 3:13 pm Jesper Kristensen, ***@***.***> wrote: I noticed today that dynamic imports now works with the latest eslint release, even though this issue has not been updated. — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#11803?email_source=notifications&email_token=AAQHWXSQJNYFR5Y42HDQAVDQHNTQRA5CNFSM4HS4GGTKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOD5T4EIQ#issuecomment-526893602>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAQHWXRZWPVRNMWFGFTKFGDQHNTQRANCNFSM4HS4GGTA> .

[mysticatea]

This issue is updated. See the issue description; we have not done the last item "ESLint Update 2: the following stuff look like to need update, but breaking changes.", we will do it on 7.0.0 release.

The syntax support is not completed, but you can use ecmaVersion:2020 since ESLint 6.2.0.
See https://eslint.org/blog/2019/08/eslint-v6.2.0-released

[jesperkristensen]

Oh, the issue was updated, it's just GitHub that only sends notifications when a new comment is added, but not when a comment is edited.

[mercmobily]

Question: is everything except "ESLint Update 2: the following stuff look like to need update, but breaking changes." been released in the NPM distributed package?

[mysticatea]

Yes. Those are in 6.2.0.

[tituswoo]

Edit: This answered my question: #12310 😄

---

👋 Hey folks! I've been trying to get dynamic imports working with eslint 6.4.0 but haven't had luck getting it to work. It's my understanding from this issue, this PR, and v6.2.0 changelog that dynamic imports should be working as of eslint 6.2, right? However eslint v6.4.0 is still throwing the following error for me whenever I attempt to use a dynamic import 😭

0:0 error  Parsing error: Invalid ecmaVersion

Also, @mysticatea I'm probably missing something really obvious, 😅 but in my .eslintrc.json, eslint is complaining about 2020 not being a valid ecmaVersion:

"parserOptions": {
    "sourceType": "module",
    "ecmaVersion": 2020
},

This issue is updated. See the issue description; we have not done the last item "ESLint Update 2: the following stuff look like to need update, but breaking changes.", we will do it on 7.0.0 release.

The syntax support is not completed, but you can use ecmaVersion:2020 since ESLint 6.2.0.
See https://eslint.org/blog/2019/08/eslint-v6.2.0-released

Thanks for the help! 🙏

[mysticatea]

You are looking using old ESLint or at least old parser. Please open a new issue with our issue template.

[mdjermanovic]

no-compare-neg-zero rule: should recognize BigInt literals.

BigInt type doesn't have negative zero value?

Object.is(-0n, 0n); // true

So perhaps no-compare-neg-zero shouldn't report bigint literals? Or maybe it still should, for the case if user might be unaware of this fact. But then it could be useful to report any occurrence of -0n in the code (not just comparisons), maybe behind an option or in a new rule?

no-extend-native rule: should recognize BigInt function.

This seems to already work by itself:

• Demo with /* eslint-env es2020 */

• Demo with /* global BigInt */

I guess it works with a manually added BigInt ESLint global since v11.6.0 of the globals package.

[ljharb]

It should probably warn on any occurrence if -0n