Add a minimal spec by gsathya · Pull Request #35 · tc39/proposal-slice-notation

gsathya · 2020-06-23T21:50:24Z

Loosely based on feedback in #1 and #19

Adds a @@slice property on Array.prototype, %TypedArray%.prototype, ArrayBuffer.prototype, SharedArrayBuffer.prototype
Aliases this slice property to the existing slice methods on these objects (similar to @@iterator and .values())
Does not include Strings because the current String.prototype.slice behavior might not be what you want (see https://mathiasbynens.be/notes/javascript-unicode#other-issues by @mathiasbynens)
Does not include the stride argument (at least not yet)
Does not allow splice

Fixes #1, fixes #16, fixes #9, fixes #33, fixes #19

leobalter

These are just suggestions for using AssignmentExpression instead of Expression (I also mentioned it at #16).

I'd be fine to address this in a separate PR/issue.

leobalter

nit picks

ljharb

I see syntax for obj[x : y], but not for obj?.[x : y], which I'd expect for consistency with optional bracket access.

ljharb · 2020-06-23T22:43:25Z

+  <h1>Properties of the Array Prototype</h1>
+  <emu-clause id="sec-array.prototype-@@slice">
+    <h1>Array.prototype [ @@slice ] (start, end)</h1>
+    <p> The initial value of the @@slice property is the same function object as the initial value of the `Array.prototype.slice` property. </p>


Suggested change

 The initial value of the @@slice property is the same function object as the initial value of the `Array.prototype.slice` property. 

 The initial value of the @@slice property is %Array.prototype.slice%.

This (and the ones below) are directly copied from the spec text: https://tc39.es/ecma262/#sec-array.prototype-@@iterator

Do you prefer to have different (but more concise) text than the spec? I'm ok with either.

Good call; I’ll make a PR to update the spec itself.

In that case, I'll leave this as is (consistent with spec ) for now and update it once the spec is changed.

@gsathya this has now been updated in the main spec.

ljharb · 2020-06-23T22:43:40Z

+  <h1>Properties of the %TypedArray.prototype% Object</h1>
+  <emu-clause id="sec-properties-of-the-%typedarrayprototype%-@@slice">
+    <h1>%TypedArray%.prototype [ @@slice ] (start, end)</h1>
+    <p> The initial value of the @@slice property is the same function object as the initial value of the `%TypedArray%.prototype.slice` property. </p>


Suggested change

 The initial value of the @@slice property is the same function object as the initial value of the `%TypedArray%.prototype.slice` property. 

 The initial value of the @@slice property is `%TypedArray.prototype.slice%`.

ljharb · 2020-06-23T22:43:52Z

+  <h1>Properties of the ArrayBuffer Prototype Object</h1>
+  <emu-clause id="sec-properties-of-the-arraybuffer-prototype-@@slice">
+    <h1>ArrayBuffer.prototype [ @@slice ] (start, end)</h1>
+    <p> The initial value of the @@slice property is the same function object as the initial value of the `ArrayBuffer.prototype.slice` property. </p>


Suggested change

 The initial value of the @@slice property is the same function object as the initial value of the `ArrayBuffer.prototype.slice` property. 

 The initial value of the @@slice property is `%ArrayBuffer.prototype.slice%`.

ljharb · 2020-06-23T22:44:06Z

+  <h1>Properties of the SharedArrayBuffer Prototype Object</h1>
+  <emu-clause id="sec-properties-of-the-sharedarraybuffer-prototype-@@slice">
+    <h1>SharedArrayBuffer.prototype [ @@slice ] (start, end)</h1>
+    <p> The initial value of the @@slice property is the same function object as the initial value of the `SharedArrayBuffer.prototype.slice` property. </p>


Suggested change

 The initial value of the @@slice property is the same function object as the initial value of the `SharedArrayBuffer.prototype.slice` property. 

 The initial value of the @@slice property is `%SharedArrayBuffer.prototype.slice%`.

rbuckton · 2020-06-24T00:45:40Z

@gsathya: This also seems to address the main issue of #19, as I was specifically requesting an @@slice symbol in that issue. There were some additional ideas in that issue, but could be opened as separate issues or as a follow-on proposal.

Co-authored-by: Leo Balter <leonardo.balter@gmail.com>

Change _fromeference_ to _fromReference_ Co-authored-by: Ron Buckton <ron.buckton@microsoft.com>

gsathya · 2020-06-24T08:16:58Z

@leobalter, @ljharb, @rbuckton, Thank you for the reviews! I've addressed almost all the comments, please let me know if I missed something.

hax · 2020-07-11T19:22:43Z

README still miss the introduction of @@slice.

gsathya · 2020-07-21T13:17:39Z

README still miss the introduction of @@slice.

Thanks for the heads up! Filed #38 to track this.

Add a minimal spec

ec1c6e4

gsathya requested review from rbuckton and syg June 23, 2020 21:50

leobalter reviewed Jun 23, 2020

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leobalter suggested changes Jun 23, 2020

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ljharb reviewed Jun 23, 2020

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gsathya and others added 4 commits June 24, 2020 08:05

Use AssignmentExpression

c4fd41f

Co-authored-by: Leo Balter <leonardo.balter@gmail.com>

Fix typo

a121681

Change _fromeference_ to _fromReference_ Co-authored-by: Ron Buckton <ron.buckton@microsoft.com>

Update spec text

8edf691

Add optional chaining integration and refactor

bfa2dd3

gsathya merged commit e02ff2d into master Jun 29, 2020

JLHwung mentioned this pull request Jul 3, 2020

[parser] Add support for slice notation babel/babel#10596

Closed

	<p> The initial value of the @@slice property is the same function object as the initial value of the `Array.prototype.slice` property. </p>
	<p> The initial value of the @@slice property is %Array.prototype.slice%.</p>

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gsathya commented Jun 23, 2020 •

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