Extensibility example

[dev101]

Hi Leland, thanks for making this extension, this is really a missing piece in KO!

Could you provide some extensibility examples (maybe in a separate file)?

I want to edit my objects in a table-like grid editor, and need add more array functions (to assign as row-level actions to manipulate array members):

• .insertAbove(index) - a shortcut to .splice(index, 0, {})
• .insertBelow(index) - a shortcut to .splice(index+1, 0, {})
• .moveUp(index) - swap elements at [index] and [index-1]
• .moveDown(index) - swap elements at [index] and [index+1]

(as I have dozens of object types, and don't wont to implement these methods for each type).

I can see you provided extensibility endpoint, but am reluctant to use it being not familiar with KO's extenders syntax.

I believe making such example would take minutes of your time, and would be very useful for users of knockout-oftype!

[lelandrichardson]

Hi @dev101 - no problem! Sorry for not getting back sooner, my notification emails for github seem to keep getting buried.

the line you referenced:

ko.observableArray.fn.ofType.fn = newMethods;

is used in the .ofType "constructor" function as seen here:

extend(interceptor, newMethods);

which basically means that whatever methods you "tack on" to ko.observableArray.fn.ofType.fn, they will be present on instances of those observable arrays.

For example, typically in JS to provide one of your extender methods like you've done above, you might do the following:

Array.prototype.insertAbove = function(index){
    return this.splice(index,0,{});
};

To provide the same behavior to the observable arrays, you would simply use:

ko.observableArray.fn.ofType.fn.insertAbove = function(index){
    return this.splice(index,0,{}); // in this case, `this` is the ko.observableArray().ofType() instance
};

Is that any more clear? I can go into more detail if you'd like.

[dev101]

well, i tried that insertAbove example, but got an error at line #24. See the fiddle.

[dev101]

I think found the reason - a typo in splice(). See pull request https://github.com/lelandrichardson/knockout-oftype/pull/2

[dev101]

You may want to refer to this fiddle in documentation as example featuring usage of ofType extensions along with delegatedEvents plugin to create type-agnostic grid actions widget operating across different kinds of typed objects.

Thanks again for plugin.