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How to process binding : foreach after altering data in observableArray

I am altering an observableArray, modifying some data in a subscribe event. First I am converting the ObservableArray using ko.toJS(), mapping trough the data, and altering. At the end I call self.menuCategories(jsArray) to set the observableArray again.
It seems like I lose the "connection" to the observableArray in some way, since the foreach statement in my code suddenly breaks.
Either there is a very much easier way to handle this, or I am not handling the observables correctly.
CODE :
var MenuWizardModel = function() {
var self = this;
self.menuCategories = ko.observableArray();
self.commonDiscount = ko.observable(0);
// Handling adding items to menuCategories.
self.addNewSubMenuItem = function () {
var newSubMenuItem = new SubMenuItemViewModel(self.newSubMenuItemName(), []);
self.menuCategories.push(newSubMenuItem);
self.newSubMenuItemName(null);
self.createNewSubMenu(false);
}
function SubMenuItemViewModel(name, foodItemList) {
var self = this;
self.name = ko.observable(name);
self.foodItemList = ko.observableArray(foodItemList);
}
self.commonDiscount.subscribe(function(val) {
var discount = parseInt(val) / 100;
var jsArray = ko.toJS(self.menuCategories);
console.log(jsArray)
jsArray = ko.toJS(jsonArray[0].foodItemList.map(item => {
item.price = parseInt(item.price) - (parseInt(item.price) * discount);
return item;
}));
self.menuCategories(jsArray);
});
MARKUP :
<div data-bind="foreach: menuCategories">
<h4 data-bind="text: name"></h4>
<div data-bind="foreach: foodItemList" class="list-group">
...
DATA :

I think the best way to handle this type of thing is to add a computed observable to the fooditem that captures the global discount and calculates the discounted price.
something like the following.
var MenuWizardModel = function() {
var self = this;
self.menuCategories = ko.observableArray([{
name: 'Main Meals'
}]);
self.commonDiscount = ko.observable(0);
self.newSubMenuItemName = ko.observable();
// Handling adding items to menuCategories.
self.addNewSubMenuItem = function() {
var newSubMenuItem = new SubMenuItemViewModel(self.newSubMenuItemName(), [{name: 'Oranges', price: 3.99}]);
self.menuCategories.push(newSubMenuItem);
self.newSubMenuItemName(null);
//self.createNewSubMenu(false);
}
function mapFoodItem(item){
item.discountedPrice= ko.pureComputed(function(){
var discount = parseInt(self.commonDiscount()) / 100
return parseInt(item.price) - (parseInt(item.price) * discount);
});
return item;
}
function SubMenuItemViewModel(name, foodItemList) {
var self = this;
self.name = ko.observable(name);
self.foodItemList = ko.observableArray(foodItemList.map(mapFoodItem));
}
};
ko.applyBindings(new MenuWizardModel());
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.4.2/knockout-min.js"></script>
<label>Discount <input data-bind="value: commonDiscount"></label>
<label>Sub Menu Name: <input data-bind="value: newSubMenuItemName" /></label>
<button data-bind="click: addNewSubMenuItem">Add Sub Menu</button>
<div data-bind="foreach: {data: menuCategories, as: 'menu' }">
<h4 data-bind="text: menu.name"></h4>
<div data-bind="foreach: {data: menu.foodItemList, as: 'food'}" class="list-group">
<div class="list-group-item">
Name: <span data-bind="text: food.name"></span>
Price: <span data-bind="text: food.price"></span>
Discounted Price: <span data-bind="text: food.discountedPrice"></span>
</div>
</div>
</div>

Hide button everywhere besides specific URL in knockout

I have the following button:
<button class="btn actionButtonIcon" id="DashboardEdit" data-bind="click: changeButtonText">
<figure>
<img src="../../../Images/NotesPink.png" />
<figcaption data-bind="text: $data.ProcurementbuttonText() ? 'Save': 'Edit'"></figcaption>
</figure>
</button>
I want to only show it in this specific url
http://localhost:5595/#scorecard/ec5aa8ed-2798-4e71-b13d-f3e525994538/dashboard/PrefDashBoard
Bearing in mind that ec5aa8ed-2798-4e71-b13d-f3e525994538 is an id, thats always changing but i want it to show with all ids as well for example the button should show here as well
http://localhost:5595/#scorecard/2356789-234-234d-g3g3-reg456452/dashboard/PrefDashBoard
and i want to hide it where this isnt the url.
I tried the following code but it doesnt seem to work:
<script>
$(document).ready(function(){
if(window.location.pathname.match(/\/dashboard/PrefDashBoard))
{
$(".DashboardEdit").show();
}
else
{
$(".DashboardEdit").hide();
}
});
</script>
Here is the JS of that button:
self.ProcurementbuttonText = ko.observable(false);
self.changeButtonText = function(){
self.ProcurementbuttonText(!self.ProcurementbuttonText())
if (!self.ProcurementbuttonText()){
var data = {
'ScorecardId':ko.observable(localStorage.getItem('scorecardId'))(),
'DashboardConfig':ko.observable(localStorage.getItem('ElementDataWidget'))()
};
PreferentialProcurementDashboardApi.Save(data);
}
}
self.DashboardEdit = ko.computed({
read: function () {
var text = 'Customise your dashboard';
if (!self.EnableScorecardFeatures()) {
text = 'This feature is currently unavailable for this scorecard type';
} else {
if (!self.HasDocumentsRole()) {
text = 'You do not have sufficient rights to access the Supporting Documents view';
}
}
return text;
}
});

i think you can take advantage of the visible binding to show/hide the button based on your criteria
function PageViewModel() {
var self = this;
self.buttonVisible = ko.observable(true);
self.changeButtonText = function() {
self.ProcurementbuttonText(!self.ProcurementbuttonText());
}
self.ProcurementbuttonText = ko.observable(false);
self.buttonText = ko.pureComputed(function() {
return self.ProcurementbuttonText() ? "Save" : "Edit";
});
self.isButtonVisible = ko.computed(function() {
//do some your logic here. just need to return a true or false value;
return self.buttonVisible();
});
self.labelText = ko.pureComputed(function() {
var messageStart = "click to ";
var state = self.buttonVisible() ? 'hide' : 'show';
var messageEnd = " button";
return messageStart + state + messageEnd;
});
}
ko.applyBindings(new PageViewModel());
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.4.2/knockout-min.js"></script>
<button class="btn actionButtonIcon" id="DashboardEdit" data-bind="click: changeButtonText, visible: isButtonVisible, text: buttonText">
Click me.
</button>
<br/>
<br/>
<label><span data-bind="text: labelText " ></span>
<input type="checkbox" data-bind="checked: buttonVisible" />
</label>

If you have Durandal's router plugin installed and configured, you can also use the activeInstruction() observable to get info about the current route. You can then use this in your computed to check if the current fragment matches your page route.
More info here: http://durandaljs.com/documentation/api#class/Router/property/activeInstruction

jQuery event callback runs only once (Angular-like framework development)

I am building a JS framework to simulate AngularJS models, only for educational purposes.
The thing is: I assign a callback to run when the models(inputs) are updated, but after they run by the first time, they "disappear".
Before trying to do this using jQuery, I was trying with querySelectorAll and got stuck on the same problem.
Here it is: http://jsfiddle.net/YmY2w/
HTML
<div class="container" jd-app="test">
<input type="text" jd-model="name" value="foo" /><br />
<input type="text" jd-model="email" value="foo#foo" />
<hr />
<p>Name: {{ name }}</p>
<p>Email: {{ email }}</p>
</div>
JAVASCRIPT
(function($, window, document, undefined) {
'use strict';
// registering models
(function() {
var $app = $('[jd-app]');
var $models = $('[jd-model]', $app);
$models.each(function(index) {
UpdateModel.apply(this);
});
function UpdateModel() {
var model = { name: $(this).attr('jd-model'), value: this.value }
var re = new RegExp('{{\\s+('+ model.name +')\\s+}}', 'gm');
$('*', $app).each(function(index) {
var $this = $(this);
$this.text( $this.text().replace(re, model.value) );
});
$(this).on('keyup', UpdateModel);
}
})();
})(jQuery, window, document);
What am I doing wrong? Is there a better way to accomplish this?

The problem you're having is that when your script first sees {{ name }} it converts it to the value of the model "name". But then in your html, you have the text "foo" instead of {{ name }} (the thing you're trying to search/replace), so you aren't able to update the displayed text.
What you have to do is keep track of the individual DOM nodes (as attached to particular models) which contain the text that initially has the "{{ }}" in them with the proper model name.
I came up with a kind of ugly prototype here:
http://jsfiddle.net/YmY2w/11/
I'm not sure how flexible it is in terms of identifying the proper templated locations, but it serves as a demo for the kind of implementation I'm talking about. Also - not very efficient I would guess. (But then neither is angularjs really...)
(function($, window, document, undefined) {
'use strict';
// From http://stackoverflow.com/questions/298750/how-do-i-select-text-nodes-with-jquery
function getTextNodesIn(node, includeWhitespaceNodes) {
var textNodes = [], nonWhitespaceMatcher = /\S/;
function getTextNodes(node) {
if (node.nodeType == 3) {
if (includeWhitespaceNodes || nonWhitespaceMatcher.test(node.nodeValue)) {
textNodes.push(node);
}
} else {
for (var i = 0, len = node.childNodes.length; i < len; ++i) {
getTextNodes(node.childNodes[i]);
}
}
}
getTextNodes(node);
return textNodes;
}
// registering models
(function() {
var $app = $('[jd-app]');
var $models = $('[jd-model]', $app);
var models = [];
$models.each(function(index) {
registerModel.apply(this);
});
function registerModel() {
var model = { name: $(this).attr('jd-model'), value: this.value, domElements: [] };
var re = new RegExp('{{\\s+('+ model.name +')\\s+}}', 'gm');
$app.contents().each(function(index) {
if ($(this).text().match(re)) {
var textNodes = getTextNodesIn(this, false);
console.log(textNodes);
$.each(textNodes, function(index, elem) {
if (elem.nodeValue.match(re)) {
var text = elem.nodeValue;
var myArray = re.exec(text);
var match = myArray[0];
var firstIndex = text.indexOf(match);
var newElem = elem.splitText(firstIndex);
newElem.splitText(match.length);
model.domElements.push(newElem);
}
});
}
});
models.push(model);
$(this).on('keyup', updateModel);
$(this).trigger('keyup');
}
function updateModel() {
var $input = $(this);
$.each(models, function(index, model) {
if (model.name === $input.attr('jd-model')) {
var newVal = $input.val();
$.each(model.domElements, function(index, elem) {
elem.nodeValue = newVal;
});
}
});
}
})();
})(jQuery, window, document);

Properly using the data-bind visible property

I have a view that displays data from a foreach loop in different categories depending on the type. Each category will contain a number of users - I created an object that will check to see if the number of users in a category are more than 10 then the text for the visible bind will show. And for the category that doesn't have more than 10 it will not show the text.
My question: if the first category doesn't have 10 it won't show text does that mean that it won't also show text for the remaining categories?
Help with: the visible binding is not working even though a category would contain more than 10 and not sure why.
Here is my JSFiddle: http://jsfiddle.net/xNdJk/1/
JavaScript:
var userViewModel = function (data) {
var _self = this;
_self.Name = ko.observable(data.Name);
_self.Letter = ko.observable(data.Letter);
_self.ShowLetter = ko.computed(function () {
return (roleViewModel.UserCount > 13);
});
};
var typeViewModel = function (data) {
var _self = this;
_self.ContentType = ko.observable(data.ContentType);
_self.Name = ko.observable(data.Name);
_self.Rank = ko.observable(data.Rank);
_self.UserCount = ko.observable(data.UserCount);
_self.Users = ko.observableArray([]);
};
View:
<div class="collapse in" data-bind="template: { name: 'list', foreach: $data.Users }">
</div>
<div id="letter" data-bind="visible:ShowLetter, text: Letter"></div>

You are mixing classes and instances, you have created a secondModel class but you never instance it, here is a working example
http://jsfiddle.net/xNdJk/2/
var viewModel = function(){
this.Letter = ko.observable('Hello, World!');
this.secondModel = new secondModel();
this.shouldShowMessage = ko.computed(function() {
return (this.secondModel.UserCount() > 13);
}, this);
}
var secondModel = function(){
var self = this;
self.UserCount = ko.observable(153);
}

knockout.js - deferred databinding for modal?

I am using knockout.js to display a list of employees. I have a single hidden modal markup on the page. When the "details" button for a single employees is clicked, I want to data-bind that employee to the modal popup. I am using the ko.applyBindings(employee, element) but the problem is when the page loads, it is expecting the modal to start off as bound to something.
So I'm wondering, is there a trick/strategy to do a late/deferred databinding? I looked into virtual bindings but the documentation was not helpful enough.
Thanks!

I would like to propose a different way to work with modals in MVVVM. In MVVM, the ViewModel is data for the View, and the View is responsible for the UI. If we examine this proposal:
this.detailedEmployee = ko.observable({}),
var self = this;
this.showDetails = function(employee){
self.detailedEmployee(employee);
$("#dialog").dialog("show"); //or however your dialog works
}
I strongly agree with this.detailedEmployee = ko.observable({}), but I am in strong disagreement with this line: $("#dialog").dialog("show");. This code is placed in the ViewModel and shows the modal window, wherein fact it is View's responsibility, so we screw-up the MVVM approach. I would say this piece of code will solve your current task but it could cause lots of problems in future.
When closing the popup, you should set detailedEmployee to undefined to have your main ViewModel in a consistent state.
When closing the popup, you might want to have validation and the possibility to discard the close operation when you want to use another modal's component in the application
As for me, these points are very critical, so I would like to propose a different way. If we "forget" that you need to display data in popup, binding with could solve your issue.
this.detailedEmployee = ko.observable(undefined);
var self = this;
this.showDetails = function(employee){
self.detailedEmployee(employee);
}
<div data-bind="with: detailedEmployee">
Data to show
</div>
As you can see, your ViewModel don't know anything about how data should be shown. It knows only about data that should be shown. The with binding will display content only when detailedEmployee is defined. Next, we should find a binding similar to with but one that will display content in the popup. Let's give it the name modal. Its code is like this:
ko.bindingHandlers['modal'] = {
init: function(element) {
$(element).modal('init');
return ko.bindingHandlers['with'].init.apply(this, arguments);
},
update: function(element, valueAccessor) {
var value = ko.utils.unwrapObservable(valueAccessor());
var returnValue = ko.bindingHandlers['with'].update.apply(this, arguments);
if (value) {
$(element).modal('show');
} else {
$(element).modal('hide');
}
return returnValue;
}
};
As you can see, it uses the with plugin internally, and shows or hide a popup depending on value passed to binding. If it is defined - 'show'. If not - 'hide'. Its usage will be the as with:
<div data-bind="modal: detailedEmployee">
Data to show
</div>
The only thing you need to do is to use your favorite modals plugin. I prepared an example with the Twitter Bootstrap popup component: http://jsfiddle.net/euvNr/embedded/result/
In this example, custom binding is a bit more powerful; you could subscribe the onBeforeClose event and cancel this event if needed. Hope this helps.

The JSFiddle linked to in the answer provided by #Romanych didn't seem to work anymore.
So, I built my own example (based upon his original fiddle) with full CRUD support and basic validation using Bootstrap 3 and the Bootstrap Modal library: https://jsfiddle.net/BitWiseGuy/4u5egybp/
Custom Binding Handlers
ko.bindingHandlers['modal'] = {
init: function(element, valueAccessor, allBindingsAccessor) {
var allBindings = allBindingsAccessor();
var $element = $(element);
$element.addClass('hide modal');
if (allBindings.modalOptions && allBindings.modalOptions.beforeClose) {
$element.on('hide', function() {
var value = ko.utils.unwrapObservable(valueAccessor());
return allBindings.modalOptions.beforeClose(value);
});
}
},
update: function(element, valueAccessor) {
var value = ko.utils.unwrapObservable(valueAccessor());
if (value) {
$(element).removeClass('hide').modal('show');
} else {
$(element).modal('hide');
}
}
};
Example Usage
The View
<div data-bind="modal: UserBeingEdited" class="fade" role="dialog" tabindex="-1">
<form data-bind="submit: $root.SaveUser">
<div class="modal-header">
<a class="close" data-dismiss="modal">×</a>
<h3>User Details</h3>
</div>
<div class="modal-body">
<div class="form-group">
<label for="NameInput">Name</label>
<input type="text" class="form-control" id="NameInput" placeholder="User's name"
data-bind="value: UserBeingEdited() && UserBeingEdited().Name, valueUpdate: 'afterkeydown'">
</div>
<div class="form-group">
<label for="AgeInput">Age</label>
<input type="text" class="form-control" id="AgeInput" placeholder="User's age"
data-bind="value: UserBeingEdited() && UserBeingEdited().Age, valueUpdate: 'afterkeydown'">
</div>
<!-- ko if: ValidationErrors() && ValidationErrors().length > 0 -->
<div class="alert alert-danger" style="margin: 20px 0 0">
Please correct the following errors:
<ul data-bind="foreach: { data: ValidationErrors, as: 'errorMessage' }">
<li data-bind="text: errorMessage"></li>
</ul>
</div>
<!-- /ko -->
</div>
<div class="modal-footer">
<button type="button" data-dismiss="modal" class="btn btn-default">Cancel</button>
<button type="submit" class="btn btn-primary">Save Changes</button>
</div>
</form>
</div>
The ViewModel
/* ViewModel for the individual records in our collection. */
var User = function(name, age) {
var self = this;
self.Name = ko.observable(ko.utils.unwrapObservable(name));
self.Age = ko.observable(ko.utils.unwrapObservable(age));
}
/* The page's main ViewModel. */
var ViewModel = function() {
var self = this;
self.Users = ko.observableArray();
self.ValidationErrors = ko.observableArray([]);
// Logic to ensure that user being edited is in a valid state
self.ValidateUser = function(user) {
if (!user) {
return false;
}
var currentUser = ko.utils.unwrapObservable(user);
var currentName = ko.utils.unwrapObservable(currentUser.Name);
var currentAge = ko.utils.unwrapObservable(currentUser.Age);
self.ValidationErrors.removeAll(); // Clear out any previous errors
if (!currentName)
self.ValidationErrors.push("The user's name is required.");
if (!currentAge) {
self.ValidationErrors.push("Please enter the user's age.");
} else { // Just some arbitrary checks here...
if (Number(currentAge) == currentAge && currentAge % 1 === 0) { // is a whole number
if (currentAge < 2) {
self.ValidationErrors.push("The user's age must be 2 or greater.");
} else if (currentAge > 99) {
self.ValidationErrors.push("The user's age must be 99 or less.");
}
} else {
self.ValidationErrors.push("Please enter a valid whole number for the user's age.");
}
}
return self.ValidationErrors().length <= 0;
};
// The instance of the user currently being edited.
self.UserBeingEdited = ko.observable();
// Used to keep a reference back to the original user record being edited
self.OriginalUserInstance = ko.observable();
self.AddNewUser = function() {
// Load up a new user instance to be edited
self.UserBeingEdited(new User());
self.OriginalUserInstance(undefined);
};
self.EditUser = function(user) {
// Keep a copy of the original instance so we don't modify it's values in the editor
self.OriginalUserInstance(user);
// Copy the user data into a new instance for editing
self.UserBeingEdited(new User(user.Name, user.Age));
};
// Save the changes back to the original instance in the collection.
self.SaveUser = function() {
var updatedUser = ko.utils.unwrapObservable(self.UserBeingEdited);
if (!self.ValidateUser(updatedUser)) {
// Don't allow users to save users that aren't valid
return false;
}
var userName = ko.utils.unwrapObservable(updatedUser.Name);
var userAge = ko.utils.unwrapObservable(updatedUser.Age);
if (self.OriginalUserInstance() === undefined) {
// Adding a new user
self.Users.push(new User(userName, userAge));
} else {
// Updating an existing user
self.OriginalUserInstance().Name(userName);
self.OriginalUserInstance().Age(userAge);
}
// Clear out any reference to a user being edited
self.UserBeingEdited(undefined);
self.OriginalUserInstance(undefined);
}
// Remove the selected user from the collection
self.DeleteUser = function(user) {
if (!user) {
return falase;
}
var userName = ko.utils.unwrapObservable(ko.utils.unwrapObservable(user).Name);
// We could use another modal here to display a prettier dialog, but for the
// sake of simplicity, we're just using the browser's built-in functionality.
if (confirm('Are you sure that you want to delete ' + userName + '?')) {
// Find the index of the current user and remove them from the array
var index = self.Users.indexOf(user);
if (index > -1) {
self.Users.splice(index, 1);
}
}
};
}
Initializing Knockout with the View and the ViewModel
var viewModel = new ViewModel();
// Populate the ViewModel with some dummy data
for (var i = 1; i <= 10; i++) {
var letter = String.fromCharCode(i + 64);
var userName = 'User ' + letter;
var userAge = i * 2;
viewModel.Users.push(new User(userName, userAge));
}
// Let Knockout do its magic!
ko.applyBindings(viewModel);

I would create another observable that wraps the employee.
this.detailedEmployee = ko.observable({}),
var self = this;
this.showDetails = function(employee){
self.detailedEmployee(employee);
$("#dialog").dialog("show"); //or however your dialog works
}
Attach the click to showDetails. Then you can just call applyBindings on page load.