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[css-typed-om] Consider using properties in addition to .get/.set #310

esprehn opened this Issue Sep 22, 2016 · 3 comments


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esprehn commented Sep 22, 2016

Real properties are faster since we can cache the property lookup, ex.

element.styleMap.color // => JS VM can cache the lookup for color

It also lets the getter/setter cache the "color" => engine representation conversion where most (all?) engines convert to an enum as there's a specific method for every property.

Note we'd still need .get(name) and .set(name) to deal with custom properties, since we don't want to add more named getters, ex. map.get("--foo"). vs map["--foo"].

The disadvantage of this approach is that it means StyleMap has 400+ properties like CSSStyleDeclaration does, and every new CSS property is implicitly adding new properties. It also means if maps get a new method called "filter", and we wanted StyleMap to be really maplike, we'd end up colliding with CSS's filter property.



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bzbarsky commented Sep 22, 2016

The name collision thing can be addressed by having an extra object:


That doesn't do anything for the other disadvantages, though.


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shans commented Apr 3, 2017

Another disadvantage is that people might think += 20;
should work.


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css-meeting-bot commented Apr 18, 2017

The CSS Working Group just discussed #310, and agreed to the following resolutions:

RESOLVED: using properties (issue #310) is moved to L2
The full IRC log of that discussion
<shane> Topic:
<dbaron> Github topic:
<fantasai> shane: I want to either say No or wait until level 2 to consider this
<fantasai> Rossen: I'd be fine for that
<fantasai> RESOLVED: using properties (issue #310) is moved to L2

@shans shans added css-typed-om-2 and removed css-typed-om-1 labels Apr 18, 2017

nainar added a commit that referenced this issue Oct 17, 2017

Merge pull request #481 from darrnshn/issue/310
[css-typed-om] Remove issue #310 from text.
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