javascript - Create new row every 2 records using knockout foreach - Stack Overflow

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I'm attempting to create a new row every two records using knockout virtual elements. My problem is that the odd record does not generate in between the two even indexes.

Here's my source HTML

   <!--ko foreach:UDGroupboxes-->
    <!--ko if:$index()%2==0 || $index()==0-->
    <div class="row-fluid">
    <!--/ko-->
        <div class="panel form-horizontal span6">
            <div class="panel-heading"><span data-bind="text:$data.Caption"></span></div>
        </div>
     <!--ko if:$index%2()!=0 && $index()!=0-->
    </div>
    <!--/ko-->
    <!--/ko-->

The output HTML

<div data-bind="attr:{id:Name}" class="tab-pane active" id="Tabsheet1">
    <!--ko foreach:UDGroupboxes-->
    <!--ko if:$index()%2==0 || $index()==0-->
    <div class="row-fluid">
    <!--/ko-->
        <div class="panel form-horizontal span6">
            <div class="panel-heading"><span data-bind="text:$data.Caption"></span></div>
        </div>
     <!--ko if:$index%2()!=0&&$index()!=0-->
    </div>
    <!--/ko-->

    <!--ko if:$index()%2==0 || $index()==0--><!--/ko-->

    <!--ko if:$index()%2==0 || $index()==0-->
    <div class="row-fluid">
    <!--/ko-->
        <div class="panel form-horizontal span6">
            <div class="panel-heading"><span data-bind="text:$data.Caption"></span></div>
        </div>
     <!--ko if:$index()%2!=0&&$index()!=0-->
    </div>
    <!--/ko-->
    <!--/ko-->
</div>

The panel should be generated no matter the condition. The condition only determines to open a new row on even numbers and close the row on odds.

I'm attempting to create a new row every two records using knockout virtual elements. My problem is that the odd record does not generate in between the two even indexes.

Here's my source HTML

   <!--ko foreach:UDGroupboxes-->
    <!--ko if:$index()%2==0 || $index()==0-->
    <div class="row-fluid">
    <!--/ko-->
        <div class="panel form-horizontal span6">
            <div class="panel-heading"><span data-bind="text:$data.Caption"></span></div>
        </div>
     <!--ko if:$index%2()!=0 && $index()!=0-->
    </div>
    <!--/ko-->
    <!--/ko-->

The output HTML

<div data-bind="attr:{id:Name}" class="tab-pane active" id="Tabsheet1">
    <!--ko foreach:UDGroupboxes-->
    <!--ko if:$index()%2==0 || $index()==0-->
    <div class="row-fluid">
    <!--/ko-->
        <div class="panel form-horizontal span6">
            <div class="panel-heading"><span data-bind="text:$data.Caption"></span></div>
        </div>
     <!--ko if:$index%2()!=0&&$index()!=0-->
    </div>
    <!--/ko-->

    <!--ko if:$index()%2==0 || $index()==0--><!--/ko-->

    <!--ko if:$index()%2==0 || $index()==0-->
    <div class="row-fluid">
    <!--/ko-->
        <div class="panel form-horizontal span6">
            <div class="panel-heading"><span data-bind="text:$data.Caption"></span></div>
        </div>
     <!--ko if:$index()%2!=0&&$index()!=0-->
    </div>
    <!--/ko-->
    <!--/ko-->
</div>

The panel should be generated no matter the condition. The condition only determines to open a new row on even numbers and close the row on odds.

• javascript
• html
• css
• knockout.js

Share Improve this question Follow edited Aug 13, 2013 at 1:05 doppelgreener 5,1241010 gold badges4848 silver badges6767 bronze badges asked Aug 9, 2013 at 22:24 StrakeStrake 76211 gold badge99 silver badges1818 bronze badges 3

• Mistype for braces () in eighth row of html source. – Vladimir Commented Aug 9, 2013 at 23:12
• I actually had caught that, just forgot to edit this post. Edited as of now. – Strake Commented Aug 12, 2013 at 15:47
• IF I want to do this every 3 items, how will it be? – Manuel Valle Commented Jan 18, 2016 at 23:53

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2 Answers 2

Sorted by: Reset to default 8

Knockout binding only happen on elements, and virtual elements must also adhere to the element hierarchy. If we take your example and use indentation to show the element relation, it looks like this:

<!--ko foreach:UDGroupboxes-->
    <!--ko if:$index()%2==0-->
        <div class="row-fluid">
            <!--/ko-->
            <div class="panel form-horizontal span6">
                <div class="panel-heading"><span data-bind="text:$data.Caption"></span></div>
            </div>
            <!--ko if:$index()%2!=0-->
        </div>
    <!--/ko-->
<!--/ko-->

The closing and opening virtual tags within the div are ignored by Knockout. So the above just has the effect of outputting every other item.

Here is a good answer for doing grouping of array items in Knockout: https://stackoverflow./a/10577599/1287183

You're better off supplying knockout with a multi-dimensional array. This is a much cleaner solution and has less potential for quirky results.

Look at Example 2: Note 3: in the documentation: http://knockoutjs./documentation/foreach-binding.html

<ul data-bind="foreach: { data: categories, as: 'category' }">
    <li>
        <ul data-bind="foreach: { data: items, as: 'item' }">
            <li>
                <span data-bind="text: category.name"></span>:
                <span data-bind="text: item"></span>
            </li>
        </ul>
    </li>
</ul>

<script>
var viewModel = {
    categories: ko.observableArray([
        { name: 'Fruit', items: [ 'Apple', 'Orange', 'Banana' ] },
        { name: 'Vegetables', items: [ 'Celery', 'Corn', 'Spinach' ] }
    ])
};
ko.applyBindings(viewModel);
</script>

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