Knockoutjs.com - Hello World Example

http://knockoutjs.com/examples/helloWorld.html

HTML

<script src="http://knockoutjs.com/downloads/knockout-3.2.0.js"></script>
<script src="https://rawgit.com/RobinHerbots/jquery.inputmask/3.x/dist/jquery.inputmask.bundle.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout-validation/2.0.3/knockout.validation.js"></script>
<div>   
    <p>Title 1: <input data-bind='value: title1' /></p> 
    <p>Amount 1: <input data-bind='value: amount1' /></p> 
    <p>Title 2: <input data-bind='inputmask: { value: title2, mask: "*****" }' />
        <span data-bind="validationMessage: title2"></span>
    </p> 
    <p>Amount 2: <input data-bind='inputmask: { value: amount2, mask: "money" }' />
    <span data-bind="validationMessage: amount2"></span>
    </p>
</div>

JavaScript

ko.bindingHandlers.inputmask =
    {
        init: function (element, valueAccessor, allBindingsAccessor) {
            var mask = valueAccessor();
            var observable = mask.value;
            
            if (ko.isObservable(observable)) {
                $(element).on('focusout change', function () {
                    if ($(element).inputmask('isComplete')) {
                        observable($(element).val());
                    } else {
                        observable(null);
                    }
                });
            }
            
            if (mask.mask === "money") {
                $(element).inputmask('decimal',
                                     {
                                         'alias': 'numeric',
                                         'groupSeparator': ',',
                                         'autoGroup': true,
                                         'digits': 2,
                                         'radixPoint': ".",
                                         'digitsOptional': false,
                                         'allowMinus': false,
                                         'prefix': '$ ',
                                         'placeholder': '0'
                                     }
                                    );
            } else {
                if (mask.regex)
                    $(element).inputmask('Regex', { regex: mask.mask });
                else
                    $(element).inputmask(mask.mask);
            }
        },
        update: function (element, valueAccessor, allBindings, viewModel, bindingContext) {
            var mask = valueAccessor();
            var observable = mask.value;
            
            if (ko.isObservable(observable)) {
                var valuetoWrite = observable();
                $(element).val(valuetoWrite);
            }
        }
    };

var ViewModel = function() {
    var self = this;

    self.convertMoneyToFloat = function...