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gibson042 opened this issue Mar 5, 2015 · 8 comments
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Return null from .attr when attributes don't exist #2118

gibson042 opened this issue Mar 5, 2015 · 8 comments
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Attributes Behavior Change

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@gibson042
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.attr("nonexistent") currently returns undefined, probably from the days before .prop. But the native DOM getAttribute and Sizzle.attr both return null in such cases. Also, .attr( name, null ) removes attributes, and it would be very convenient to allow universal round-tripping.

Let's consider changing the return value to accommodate.

Note that setter treatment of undefined is explicitly out-of-scope for this ticket, as are .prop and .data round-tripping, although those are certainly related topics.
@gibson042 gibson042 added this to the 3.0.0 milestone Mar 5, 2015
@winhowes winhowes mentioned this issue Mar 9, 2015
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@timmywil
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timmywil commented Mar 9, 2015

@dmethvin We're leaning towards doing this for beta. Do you know of a use case that would make this catastrophic?

@dmethvin
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dmethvin commented Mar 9, 2015

It seems like returning null is a good idea, although who knows what it will break in the wild. The only way to find out is to change it! We should continue to return undefined for empty jQuery collections tho.

@gibson042
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We should continue to return undefined for empty jQuery collections tho.

Thanks; that reminded me to create #2134.

timmywil pushed a commit that referenced this issue Mar 16, 2015
@winhowes @timmywil
Attributes: return null when attribute does not exist
afca031 
Fixes gh-2118
Close gh-2129

Conflicts:
	test/unit/attributes.js
@scottgonzalez
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It seems like returning null is a good idea, although who knows what it will break in the wild.

Of course the answer turns out to be jQuery UI :-)

I'm working on updates right now.

@scottgonzalez scottgonzalez mentioned this issue Mar 25, 2015
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@timmywil
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The team decided to revert this due to breakages in UI and mobile.

timmywil added a commit that referenced this issue Mar 30, 2015
@timmywil
Attributes: revert returning null for non-existant attributes
7bce5b0 
Ref #2118
timmywil added a commit to timmywil/jquery that referenced this issue Mar 30, 2015
@timmywil
Attributes: revert returning null for non-existant attributes
2905961 
Ref jquery#2118
@gibson042 gibson042 mentioned this issue May 16, 2015
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@mgol mgol removed the Needs review label Jul 31, 2015
markelog pushed a commit that referenced this issue Nov 10, 2015
@winhowes @markelog
Attributes: return null when attribute does not exist
bbfcf9b 
Fixes gh-2118
Close gh-2129
timmywil added a commit that referenced this issue Nov 10, 2015
@timmywil @markelog
Attributes: revert returning null for non-existant attributes
bc9ca0b 
Ref #2118
@dmethvin
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We backed this out for 1.12/2.2 which definitely seems right, but it's also excluded from 3.0. Should it be? That is, do we want a non-existent attribute to return null as proposed here? If not I want to remove the milestone and tag.

@mgol mgol removed this from the 3.0.0 milestone Mar 23, 2016
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mgol commented Mar 23, 2016

I removed the milestone due to the revert and opened the issue & added the "Needs review" label to account for the Dave's question.

@mgol mgol reopened this Mar 23, 2016
@markelog
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We backed this out for 1.12/2.2 which definitely seems right, but it's also excluded from 3.0. Should it be?

I remember this discussion, we reverted cause it might be dangerous to do which proved the UI breakage, where is literally no gain from, except to align with standard, whereas behaviour in DOM spec is very questionable in the first place, since in all others JS API you get undefined value not null value

@cssmagic cssmagic mentioned this issue May 18, 2016
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@scottgonzalez @dmethvin @timmywil @markelog @gibson042 @mgol