KnockoutJS + Advanced Checkbox Function

This checkbox is advanced in that not only is it checked based on existing data, but the page also needs to react in several ways when the user changes the checkbox by manually checking or unchecking the checkbox.

Imagine you have murderCaseModel

a list of different Witnesses

crimes for.

Here's a script for you:

The requirements are as follows:

Already done

  • If the previous ones Witnesses

    exist from the loaded data, set the status checked

    for the page load window

    <input type='checkbox' data-bind='checked: numWitnesses() > 0'></input>

  • Delete Witness

  • Add to Witness


Enabling a checkbox causes another region to appear or disappear on the page

  • If the user switches to None (not checked), we create an INVISIBLE witness display area (ideally, remove from the DOM) and remove all objects Witness

  • If it is toggled to Yes (checked), we create a VISIBLE witness viewport and make sure that the user has at least one object Witness

    to be populated by the user.

This whole problem is very complicated for me and defines the auto value for the checkbox, but also the user-selected value for which it is difficult to understand. Any help is much appreciated. This is awesome functionality!


source to share

2 answers

You can use computed

to make the field a wereThereAnyWitnesses

little smarter:

self.wereThereAnyWitnesses = ko.computed({
    read: function() {
        return self.numWitnesses() > 0;
    write: function(wereThereAnyWitnesses) {
        if (!wereThereAnyWitnesses && self.numWitnesses() > 0) {
            if (!confirm("Remove all current witnesses?"))
                return self.wereThereAnyWitnesses.notifySubscribers();

        if (wereThereAnyWitnesses && self.numWitnesses() == 0)
}, this);


And in your HTML:

<input type='checkbox' data-bind='checked: wereThereAnyWitnesses' />


See Fiddle



You can use jQuery. First, make sure you include the jQuery libraries in your header tags. Just copy the following code into your headers:

<script src=""></script>


Then, use the following code to check if the checkbox is checked:

<script type="text/javascript">
if ($('#the_checkbox').is(":checked"))


And here is the input:

<input type="checkbox" id="the_checkbox" />




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