#429 — Array.prototype.splice called with single argument should match de-facto standard

bug_id: 429
creation_ts: 2012-07-03 12:33:00 -0700
short_desc: Array.prototype.splice called with single argument should match de-facto standard
delta_ts: 2013-08-23 08:22:21 -0700
product: Draft for 6th Edition
component: normative change from ES5.x
version: Rev 8: June 15, 2012 Draft
rep_platform: All
op_sys: All
bug_status: RESOLVED
resolution: FIXED
bug_file_loc: http://mathias.html5.org/specs/javascript/#array.prototype.splice
priority: Normal
bug_severity: enhancement
everconfirmed: true
reporter: Luke Hoban
assigned_to: Allen Wirfs-Brock
cc: ["john.david.dalton", "mathias"]

commentid: 1073
comment_count: 0
who: Luke Hoban
bug_when: 2012-07-03 12:33:32 -0700

Per discussion on the wiki recently [0] as well as two years ago [1], the now de-facto standard behavior of splice with a single argument should be included in the ES6 specification.

[0] https://mail.mozilla.org/pipermail/es-discuss/2012-July/023875.html
[1] https://mail.mozilla.org/pipermail/es-discuss/2010-October/012012.html

commentid: 1074
comment_count: 1
who: John-David Dalton
bug_when: 2012-07-03 14:28:23 -0700

The title should be "Array.prototype.splice" and not "String.prototype.splice".

commentid: 1078
comment_count: 2
who: Mathias Bynens
bug_when: 2012-07-03 22:56:34 -0700

I’ve documented this here, for now: http://mathias.html5.org/specs/javascript/#array.prototype.splice

This can easily be fixed in the ECMAScript spec by adding an extra step to the algorithm (http://ecma-international.org/ecma-262/5.1/#sec-15.4.4.12) saying:

> If `deleteCount` is `undefined`, set the value of `deleteCount` to `Infinity`.

commentid: 1079
comment_count: 3
who: Mathias Bynens
bug_when: 2012-07-03 22:57:54 -0700

Tests: http://mathias.html5.org/tests/javascript/array/

commentid: 1080
comment_count: 4
who: John-David Dalton
bug_when: 2012-07-03 23:02:17 -0700

In Chrome at least array.splice() will return [], so stating `undefined` won't
work as also `array.splice(start, void 0) currently is treated as`0`. It seems
to be only when the arguments.length of `Array#splice` is equal to 1 that the
extension kicks in.

commentid: 1085
comment_count: 5
who: Mathias Bynens
bug_when: 2012-07-04 00:10:03 -0700

Good catch, JDD! Actually, another special case applies to the first argument.

I guess something among the lines of the following could be added to the algorithm:

1. If the `start` argument is omitted (`arguments.length == 0`), set its value to `Infinity`.
2. If the `deleteCount` argument is omitted (`arguments.length < 2`), set its value to `Infinity`.

(I’ve updated the abovementioned spec and tests.)

commentid: 1087
comment_count: 6
who: John-David Dalton
bug_when: 2012-07-04 00:17:20 -0700

There is no need to address the `arguments.length` equals `0` case as the existing logic/rules in the spec cover it. For the case of `arguments.length` equals `1` the `actualDeleteCount` would be `len – actualStart`.

commentid: 4913
comment_count: 7
who: Allen Wirfs-Brock
bug_when: 2013-08-15 16:02:21 -0700

fixed in rev17 editor's draft

commentid: 5060
comment_count: 8
who: Allen Wirfs-Brock
bug_when: 2013-08-23 08:22:21 -0700

fixed in rev17, August 23, 2013 draft

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#429 — Array.prototype.splice called with single argument should match de-facto standard