Knockout.js show / hide block visibility pattern

Question

I have the code duplication problem in the next case. On my page I have a lot of blocks that I need to show / hide by clicking to link:

<div>
    <a data-bind="click: showHiddenFirst, visible: isVisibleFirst"href="#">Show first</a>
    <div data-bind="visible: !isVisibleFirst()" style="display:none">
        hidden content first
    </div>
</div>
<div>
    <a data-bind="click: showHiddenSecond, visible: isVisibleSecond"href="#">Show second</a>
    <div data-bind="visible: !isVisibleSecond()" style="display:none">
        hidden content second
    </div>
</div>

And my JS

var vm = function(){
    this.isVisibleFirst = ko.observable(true);

    this.showHiddenFirst = function(){
        this.isVisibleFirst(false)
    };

    this.isVisibleSecond = ko.observable(true);

    this.showHiddenSecond = function(){
        this.isVisibleSecond(false)
    };
};

ko.applyBindings(new vm());

Here is jsfiddle example http://jsfiddle.net/sstude/brCT9/2/

Question is how to avoid all this show / visible duplication? Maybe I need some custom binding where I put id of my hidden block or smth. else? Any patterns that you can suggest?

Answer 1

Here was a thought at encapsulating this functionality completely in an observable for your specific scenario:

ko.bindingHandlers.clickVisible = {
    init: function(element) {
       var visible = ko.observable(true),
           opposite = ko.computed(function() { return !visible(); }),
           clickHandler = visible.bind(null, false);

        //apply bindings to anchor
        ko.applyBindingsToNode(element, { click: clickHandler, visible: visible });

        var sibling = element.nextSibling;
        //find the div (as text nodes, etc. will show up in nextSibling)
        while (sibling && sibling.nodeType != 1) {
            sibling = sibling.nextSibling;   
        }        

        //apply bindings to div
        if (sibling) {
            ko.applyBindingsToNode(sibling, { visible: opposite });
        }
    }
};

It could be tweaked further, as necessary, if maybe the value passed into the binding should matter.

Example: http://jsfiddle.net/rniemeyer/gCgy5/