If babel doesn't implement it either, don't count against it by hzoo · Pull Request #30 · babel/babel-preset-env

hzoo · 2016-11-02T03:53:35Z

Didn't get to this at the time and the fix is actually pretty simple I think?

@jdalton mentioned in b80dfaa#commitcomment-19652847 that node 4 supports arrow-functions. It's a similar thing for other transforms which I noticed before but didn't look into. This seems to change a bunch to node 4.

the entries babel is failing at (or w/ non-spec option)

arrow functions/correct precedence

arrow functions/no "prototype" property
arrow functions/lexical "super" binding in constructors
arrow functions/lexical "new.target" binding
class/computed names, temporal dead zone
class/extends null
class/new.target
super/statement in constructors
super/expression in constructors
super/constructor calls use correct "new.target" binding
super/super() invokes the correct constructor
destructuring, parameters/new Function() support
destructuring, parameters/defaults, separate scope
destructuring, parameters/defaults, new Function() support
function "name" property/new Function
function "name" property/bound functions
function "name" property/accessor properties
function "name" property/symbol-keyed methods
function "name" property/object methods (class)
function "name" property/isn't writable, is configurable
Unicode code point escapes/in identifiers
default function parameters/temporal dead zone
default function parameters/separate scope
default function parameters/new Function() support
rest parameters/can't be used in setters
rest parameters/new Function() support
spread (...) operator/with sparse arrays, in array literals
spread (...) operator/spreading non-iterables is a runtime error
RegExp "y" and "u" flags / "y" flag
RegExp "y" and "u" flags / "y" flag, lastIndex
template literals/toString conversion
generators/can't use "this" with new
generators/%GeneratorPrototype%.constructor
generators/yield * on non-iterables is a runtime error

Details

hzoo · 2016-11-02T03:53:58Z

data/plugins.json

-    "firefox": 3,
-    "safari": 10,
-    "node": 6
+    "chrome": -1,


This one is interesting since it seems as if the transform doesn't actually work or the compat-table is wrong for babel's data?

Jessidhia · 2016-11-02T04:39:27Z

data/plugins.json

    "firefox": 45,
    "safari": 10,
-    "node": 6
+    "node": 4


The Function.name will be incorrect, and the function-name transform can only fix it for transformed arrow functions.

Though I think that is the case with Node 6 too (but should be fixed in Node 7).

var a = ()=>1 a.name // is '' in v4, 'a' in v6 & v7. Object.defineProperty(a, 'name', { 'value': 'a', 'configurable': true }); a.name // is 'a' in v4

In my arrow function use at least, name wasn't a stopper. @sindresorhus

Yeah, it's definitely not a stopper, though it might make things more confusing when debugging, especially for functional React components.

Interestingly out of Chrome, Edge, Firefox, and Safari, it's Firefox 49 (current stable) that still displays "" for a.name while the others display "a".

Jessidhia · 2016-11-02T04:42:59Z

data/plugins.json

    "firefox": 45,
    "safari": 10,
-    "node": 5
+    "node": 4


Node 4 doesn't support spread, so non-transformed classes that have super(...args) will not run.

class X extends Y { constructor (...args) { super(...args) } }

is invalid in node 4 regardless of the other transforms. That example constructor is useless as that is the default implementation, but when transform-class-properties runs, it has to generate a constructor with that content to attach the public property initializers:

class X extends Y { z = null }

transforms to:

class X extends Y { constructor (...args) { super(...args) this.z = null } }

Is it possible to change spread to account for this? Or do we need to check if a user is using spread.. or make another option

Ok I guess we'll need to figure out a good way to override this or just not do this PR

I wrote, a long time ago in phabricator (no idea on the bug number), that transform-rest-spread should, at least, detect if super with spread is being used, and bail if transform-es2015-classes is not also being used.

hzoo · 2017-03-29T03:49:33Z

Closing for now, doing this may cause more issues

jdalton · 2017-03-29T03:51:49Z

Is there a way to opt-out of transforms? For example, say I don't want to transform arrow functions in Node 4 (I don't care about whatever edge case issue there is) but I still want the general Node 4 bar.

hzoo · 2017-03-29T03:53:41Z

there's the exclude option

jdalton · 2017-03-29T04:00:05Z

Something like

  "presets": [
    ["env", {
      "exclude": ["transform-es2015-arrow-functions"],
      "targets": { "node": 4 }
    }]
  ]

Following up on slevithan#108 (comment), this change adds [Babel] to the build process, with [babel-preset-env] to ensure browser compatibility. It defaults to supporting all ES5 browsers, but can be tweaked in the future. To reduce potential merge conflicts, this commit intentionally omits the resulting changes to `xregexp-all.js`, but they are only formatting changes anyway (you can use a tool like [prettier-diff] to see this). In particular, `'use strict';` is prepended to every module in the bundle. Of course, this shouldn't affect the API or browser compatibility. The [transform-es2015-literals] plugin is [excluded] to avoid changing unicode strings. See slevithan#174 (comment) After this commit, a separate "build" commit should be made that updates `xregexp-all.js`. [Babel]: https://babeljs.io/ [babel-preset-env]: https://github.com/babel/babel-preset-env [prettier-diff]: https://github.com/josephfrazier/prettier-diff [transform-es2015-literals]: https://www.npmjs.com/package/babel-plugin-transform-es2015-literals [excluded]: babel/babel-preset-env#30 (comment)

Following up on #108 (comment), this change adds [Babel] to the build process, with [babel-preset-env] to ensure browser compatibility. It defaults to supporting all ES5 browsers, but can be tweaked in the future. To reduce potential merge conflicts, this commit intentionally omits the resulting changes to `xregexp-all.js`, but they are only formatting changes anyway (you can use a tool like [prettier-diff] to see this). In particular, `'use strict';` is prepended to every module in the bundle. Of course, this shouldn't affect the API or browser compatibility. The [transform-es2015-literals] plugin is [excluded] to avoid changing unicode strings. See #174 (comment) After this commit, a separate "build" commit should be made that updates `xregexp-all.js`. [Babel]: https://babeljs.io/ [babel-preset-env]: https://github.com/babel/babel-preset-env [prettier-diff]: https://github.com/josephfrazier/prettier-diff [transform-es2015-literals]: https://www.npmjs.com/package/babel-plugin-transform-es2015-literals [excluded]: babel/babel-preset-env#30 (comment)

hzoo commented Nov 2, 2016

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hzoo changed the title ~~If babel doesn't implement it correctly, don't count against it~~ If babel doesn't implement it, don't count against it Nov 2, 2016

hzoo changed the title ~~If babel doesn't implement it, don't count against it~~ If babel doesn't implement it either, don't count against it Nov 2, 2016

Jessidhia reviewed Nov 2, 2016

View reviewed changes

If babel doesn't implement it correctly, don't count against it

e21d740

hzoo force-pushed the fix-versions branch from 7e97549 to e21d740 Compare November 16, 2016 16:42

hzoo mentioned this pull request Dec 8, 2016

Use array features for symbol and array.iterator #64

Merged

This was referenced Jan 5, 2017

Features support data source #117

Closed

Update compat-table, build data #135

Merged

hzoo added the orphaned label Mar 29, 2017

hzoo closed this Mar 29, 2017

danez deleted the fix-versions branch March 29, 2017 10:01

hzoo added i: stale and removed orphaned labels Oct 3, 2017

babel-bot mentioned this pull request Oct 30, 2017

Features support data source babel/babel#6637

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