1105406 - Remove deprecated for-each-in array comprehension in about:newtab

Status: RESOLVED FIXED

(Firefox :: New Tab Page, defect)

Description

[Chris Peterson [:cpeterson]]

Attachment: 1083467_fix-newtab.patch

Bug 1083467 will log console warnings for JavaScript 1.6's deprecated for-each-in loops (including JavaScript 1.7's legacy for-each-in array comprehensions). This patch replaces a for-each-in array comprehension in about:newtab code with an ES7 for-of array comprehension.

This patch also initializes _cells to [] instead of null. for-each-in array comprehensions handle null by returning [], but for-of throws a TypeError on null.

Comment 1

[Drew Willcoxon :adw]

Comment on attachment 8529177 [details] [diff] [review]
1083467_fix-newtab.patch

Review of attachment 8529177 [details] [diff] [review]:
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Thanks.

I wondered whether anything depends on _cells starting out as null, but a search on mxr doesn't reveal anything, not even in tests.  All consumers expect cells to be an array.  So that part of this patch looks OK.

[for (cell of this.cells || []) cell.site] would be the safest thing to do since it wouldn't change the current behavior at all, but given what I just said about consumers, plus my opinion that it makes sense anyway for _cells to always be an array, I don't think that's necessary.

Comment 2

[Chris Peterson [:cpeterson]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/8e681c8b554d

Comment 3

[Phil Ringnalda (:philor)]

https://hg.mozilla.org/mozilla-central/rev/8e681c8b554d

Comment 4

[Sudhir]

Can I pick up this bug for QA? If so, can someone update the QA steps?