Click Submit Custom Binding for Form Validation

## Knockout.clickSubmit.js
ko.bindingHandlers.clickSubmit = {
    init: function(element, valueAccessor, allBindings, viewModel, bindingContext) {
        var formElement = null;

        // Allow the binding handler to function with or without jQuery
        if(typeof jQuery == 'undefined') {
            // We need to have a parameter provided to the handler if jQuery is not present
            var value = ko.utils.unwrapObservable(valueAccessor());
            if(!value)
                // Need to have a value which contains the name of our parent form.
                throw new Error('You must provide a parameter for the binding "clickSubmit" if you are not using jQuery.');
            formElement = document.forms[value];
        } else {
            var jqFormElement = $(element).closest('form');
            formElement = jqFormElement.get(0);
        }

        if(!formElement) {
            throw new Error('"clickSubmit" binding could not find the parent form')
        }

        // Create our input submit button (which will be not displayed)
        var hiddenSubmit = document.createElement('input');
        hiddenSubmit.setAttribute('type','submit');
        hiddenSubmit.style.display = 'none';

        formElement.appendChild(hiddenSubmit);

        // Wrap our new element in a function closure, so we can pass this to the framework's click binding
        var newFunction = function() {
            return function() {
                hiddenSubmit.click();
            };
        };

        ko.bindingHandlers.click.init(element, newFunction, allBindings, viewModel, bindingContext);
    }
};