Is providing a mixed type object to a custom binding handlers discouraged?

[Lau Yu Hei]

Sorry if the title is confusing. 

I study some of the code examples in Knockout documentation and found that usually properties related to the same binding handler are separated, for example in the Custom Binding example

<div data-bind="slideVisible: giftWrap, slideDuration:600">

http://knockoutjs.com/documentation/custom-bindings.html

When the handler of the custom binding slideVisible` is triggered, it will access the binding `slideDuration`, which controls the duration of the slide. However, I am curious why don't instead have syntax like

<div data-bind="slide: {visible: giftWrap, duration:600}">

In this way, it is straightforward to see that the `visible` and `duration` are related to `slide` animation, and moreover we will not "pollute" the data-bind by introducing many data binding names (`slideDuration`, `slideXXX`) for one single binding handler, not to mention user does not need to type the long name `slideDuration`, `slideComplete`, `slide...` for every property.

I do understand that in the world of programming there is not a definite way of implementing things. But I also want to know in the point of view of Knockout developers, is there any particular reason this is acceptable or discouraged? Thank you.

Cheers

[Lau Yu Hei]

The object literal `{}` is used in some of the data bindings, but is for attributes that are not directly related to each other. For example the `style`, `css` binding handlers accept an object of different HTML styles and CSS classes and their toggle condition. But compared with the example I have given in the original post it is quite different.

[Gunnar Liljas]

It's mostly a matter of taste. However, for bindings like "options", I would say that the syntax:

options: myrows, optionsText:'name'

is chosen over something like

options: {items:myrows, text:'name'}

because it allows the simplest implementation to be just

options: myrows

and the "option handlers" can be reused for other bindings, like "selectedOptions"

/G

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