I have a observable called foo and then a computed that is interconnected with foo
foo = ko.observable();
bar = ko.computed(function(){
read: function() {
var blah = parseFloat(self.foo()),
qux = blah + 1;
return qux;
},
write: function(value)
{
value = parseFloat(value);
self.foo(value - 1);
},
});
I have this textfield
<input type="text" name="foo" id="foo" placeholder="Foo" class="border-bottom" data-bind="value: foo"/>
And I have this jQuery Mobile Range Slider
<input class="ratio" type="range" name="slider-percent" min="0.00" max="100.00" data-highlight="true" step="0.1" data-bind="value: bar"/>
and then a debugging markup for KO
<pre data-bind="text: ko.toJSON($data, null, 2)"></pre>
Here are some problems that I have
When I update foo textfield, I see that the value of bar changes via the debugging markup but it does not reflect in the actual slider.
When I try to move slider around, nothing happens. Neither foo nor bar gets updated.
Is there a way to solve this problems?
Here's a working fiddle: http://jsfiddle.net/r7Ruc/1/
There was an extra function() in the computed declaration. If you use both read and write, you should pass an object to computed, not a function.
The code, because of "Links to jsfiddle.net must be accompanied by code."
var CTR = function () {
var self = this;
self.foo = ko.observable();
self.bar = ko.computed({
read: function () {
var blah = parseFloat(self.foo()),
qux = blah + 1;
return qux;
},
write: function (value) {
console.log(value);
value = parseFloat(value);
//self.share(value - 1);
},
});
}
var c = new CTR();
ko.applyBindings(c);
Related
I have a bootstrap nav-tab and I want to display dynamically content when I select a tab. Each tab must display a div with some text that is returned from ajax call at the controller's action GetSection().
<div class="tabbable">
<ul class="nav nav-tabs" data-bind="foreach: sections">
<li data-bind="css: { active: isSelected }">
<a href="#" data-bind="click: $parent.selectedSection">
<span data-bind="text: name" />
</a>
</li>
</ul>
<div class="tab-content" data-bind="foreach: sections">
<div class="tab-pane" data-bind="css: { active: isSelected }">
<span data-bind="text: 'In section: ' + retValue" />
</div>
</div>
</div>
Javascript code:
var Section = function (name, selected) {
this.name = name;
this.retValue = "";
this.isSelected = ko.computed(function () {
return this === selected();
}, this);
}
var ViewModel = function () {
var self = this;
self.selectedSection = ko.observable();
self.sections = ko.observableArray([
new Section('Tab One', self.selectedSection),
new Section('Tab Two', self.selectedSection),
new Section('Tab Three', self.selectedSection)
]);
self.selectedSection(self.sections()[0]);
self.selectedSection.subscribe(function () {
$.ajax({
url: '#Url.Action("GetSection")',
data: { name: self.selectedSection().name },
type: 'GET',
success: function (data) {
self.selectedSection().retValue=data.text;
}
});
});
}
ko.applyBindings(new ViewModel());
The problem is that retValue from ajax is not displayed. The controller action is this:
public JsonResult GetSection(string name)
{
var ret = new { text = name + "abcd" };
return Json(ret, JsonRequestBehavior.AllowGet);
}
Knockout can only know to update the view for properties that are obsverable (hence the name), so you need to make retValue observable:
var Section = function (name, selected) {
this.name = name; // <-- consider similar change here too
this.retValue = ko.observable(""); // <-- change here
this.isSelected = ko.computed(function () {
return this === selected();
}, this);
}
Then, you need to remember to set an obsverable's value by calling it as a method with the new value as its only argument, e.g.:
$.ajax({
url: '#Url.Action("GetSection")',
data: { name: self.selectedSection().name },
type: 'GET',
success: function (data) {
self.selectedSection().retValue(data.text); // <-- change here
}
});
And finally, if you're binding to a complex expression in your view you need to invoke it as a function (with no arguments) to get its value:
<span data-bind="text: 'In section: ' + retValue()" />
As a side note, realize that you can leave off the parentheses (consider it syntactic sugar from knockout) if you bind straight to just the observable, e.g.:
<span data-bind="text: retValue" />
Which is effectively equivalent to:
<span data-bind="text: retValue()" />
On a foot note, I see you've used this syntax for a click binding:
...
This works... but only by coincidence. You should realize these things together:
$parent.selectedSection contains the result of ko.observable() which means it is in fact a function that can be invoked
the click data-binding will invoke the expression it gets as a function, passing the contextual data (in your case a Section) to that function
So bascially, when the click happens, this happens:
$parent.selectedSection($data) // where $data == the current Section
Which effectively selects the Section.
It would be more verbose though a lot clearer if the $parent had a function:
var self = this;
self.selectChild = function(section) {
// Possibly handle other things here too, e.g. clean-up of the old selected tab
self.selectedSection(section);
}
And then use the click binding in this clear way:
...
On click the selectChild method will be called, again with the contextual data as the argument.
Instead of this
self.selectedSection().retValue=data.text;
Do this
self.selectedSection(data);
Im trying to apply the JQuery UI highlight effect to an element when an item that is bound to a knockout observablearray is updated.
The highlight effect is applied but the highlight color used is always the elements current background color. even if I specify the highlight color using the { color: 'XXXXXXX' } option.
any ideas what might be happening?
Thanks,
Steve.
Code below: The element is the span.tag
<div class="row">
<div class="span12">
<div class="tagsinput favs span12" style="height: 100%;" data-bind="foreach: favs, visible: favs().length > 0">
<span class="tag" data-bind="css: $root.selectedFav() == userPrefID() ? 'selected-fav' : '', attr: { id: 'fav_' + userPrefID() }">
<span data-bind="text: name, click: $root.loadFav.bind($data)"></span>
<a class="tagsinput-fav-link"><i class="icon-trash" data-bind="click: $root.delFav.bind($data)"></i></a>
<a class="tagsinput-fav-link-two" data-bind="visible: $root.selectedFav() == userPrefID()"><i class="icon-save" data-bind=" click: $root.saveFav.bind($data)""></i></a>
</span>
</div>
</div>
</div>
// This is the code that does a save via ajax then highlights the element when done.
$.getJSON('#Url.Action("SaveFav","User")', { id: item.userPrefID(), fav: window.JSON.stringify(fav) }, function (result) {
var savedFav = ko.utils.arrayFirst(self.favs(), function (aFav) {
return aFav.userPrefID() == result.userPrefID; // <-- is this the desired fav?
});
// Fav found?
if (savedFav) {
// Update the fav!
savedFav.value(result.value);
}
}).done(function () {
var elementID = "#fav_" + item.userPrefID();
highlightElement(elementID);
});
// Function to highlight the element
function highlightElement(element) {
$(element).effect("highlight", {}, 1500);
}
I would do this the 'knockout' way... use a custom bindingHandler. You shouldn't be directly manipulating DOM in your viewModel, but only touching properties of your viewModel.
Taking this approach, you simply set a boolean value to true when your save is complete... this triggers the highlight effect (the jquery/dom manipulation neatly hidden away from your viewmodel) and when highlight effect completes, the handler sets the boolean back to false. Nice and tidy.
HTML:
<div id="#fav" data-bind="highlight: done">This is a test div</div>
<br />
<button data-bind="click: save">Simulate Save</button>
Javascript:
ko.bindingHandlers.highlight = {
update: function(element, valueAccessor) {
var obs = valueAccessor();
var val = ko.unwrap(obs);
if (val) {
$(element).effect("highlight", {}, 1500, function() {
obs(false);
});
}
}
};
var vm = function() {
var self = this;
self.done = ko.observable(false);
self.save = function() {
self.done(true);
};
}
ko.applyBindings(new vm());
Fiddle:
http://jsfiddle.net/brettwgreen/pd14q4f5/
I am having trouble animating jquery knob.
As you can see in my example only the last one animates.
<input class="knob nummer1 animated" value="0" rel="64">
<input class="knob nummer2 animated" value="0" rel="77">
<input class="knob nummer3 animated" value="0" rel="99">
link
local $this object was not getting set for every new instance of knob,instead same this object was referenced each time.
so what you need to do is create a new local reference of this object for every knob instance.
var $this = $(this);
Live Demo # JSFiddle
JS CODE:
$('.knob').each(function() {
var $this = $(this);
var myVal = $this.attr("rel");
$this.knob({
});
$({
value: 0
}).animate({
value: myVal
}, {
duration: 2000,
easing: 'swing',
step: function() {
$this.val(Math.ceil(this.value)).trigger('change');
}
});
});
I have an array of checkboxes and I would like to use it as an array, for example set single iitems in a group of options and retrieve the values of the group.
For a single checkbox I'm able to set it and get the click event, as an array I don't get anything.
HTML code :
<div class="k-group" id="chkbox-options">
<label>
Red
<input type="checkbox" id="chk1" value="Red" data-bind="checked: colors" />
Green
<input type="checkbox" id="chk2" value="Green" data-bind="checked: colors" />
Blue
<input type="checkbox" id="chk3" value="Blue" data-bind="checked: colors" />
</label>
</div>
Javascript code :
<script type="text/javascript">
var colordata = null;
$(document).ready(function () {
colordata = kendo.observable({
colors: ["Blue"]
});
kendo.bind($("chkbox-options"), colordata);
$("#dump-values").click(function () {
kendoConsole.log(colordata.colors.toString());
});
$("#chk1").click(function () {
kendoConsole.log("click chk1");
if (this.checked) {
kendoConsole.log("click chk1 true");
}
});
});
</script>
I can get the click event on a single checkbox, while I cannot set the values of the checkboxes in kendo.observable in the field var colordata.
I saw a similar example in the kendo documentation but I'm not able to make it work.
Thanks for your help
Marco
couple of points:
1. in kendo.bind # is missing for the div id chkbox-options
2. you need to read the changed colors inside the change event of the the observable object. The change happens after the click event so inside click event you always see the old data.
I have corrected your jsFiddle: http://jsfiddle.net/whizkid747/rPjjJ/4/
var colordata = null;
$(document).ready(function () {
colordata = kendo.observable({
colors: ["Blue"]
});
kendo.bind($("#chkbox-options"), colordata);
colordata.bind("change", function(e) {
var selectedColors = '';
$.each(colordata.colors, function(key, value){
selectedColors = selectedColors + " " + value;
});
if(colordata.colors.length == 0){
console.log('no colors selected');
}else{
console.log('selected colors:' + selectedColors);
}
});
});
This fiddle shows how to bind a jQuery slider 'slide' event to a Knockout observable. How would this need to change to also bind the 'max' option of the slider to an observable? Do you have to create an entirely new ko.bindingsHandler entry? Or can the existing one be used?
Here is the code from the fiddle for reference.
HTML
<h2>Slider Demo</h2>
Savings: <input data-bind="value: savings, valueUpdate: 'afterkeydown'" />
<div style="margin: 10px" data-bind="slider: savings, sliderOptions: {min: 0, max: 100, range: 'min', step: 1}"></div>
Spent: <input data-bind="value: spent, valueUpdate: 'afterkeydown'" />
<div style="margin: 10px" data-bind="slider: spent, sliderOptions: {min: 0, max: 100, range: 'min', step: 1}"></div>
Net: <span data-bind="text: net"></span>
JS
ko.bindingHandlers.slider = {
init: function (element, valueAccessor, allBindingsAccessor) {
var options = allBindingsAccessor().sliderOptions || {};
$(element).slider(options);
ko.utils.registerEventHandler(element, "slidechange", function (event, ui) {
var observable = valueAccessor();
observable(ui.value);
});
ko.utils.domNodeDisposal.addDisposeCallback(element, function () {
$(element).slider("destroy");
});
ko.utils.registerEventHandler(element, "slide", function (event, ui) {
var observable = valueAccessor();
observable(ui.value);
});
},
update: function (element, valueAccessor) {
var value = ko.utils.unwrapObservable(valueAccessor());
if (isNaN(value)) value = 0;
$(element).slider("value", value);
}
};
var ViewModel = function() {
var self = this;
self.savings = ko.observable(10);
self.spent = ko.observable(5);
self.net = ko.computed(function() {
return self.savings() - self.spent();
});
}
ko.applyBindings(new ViewModel());
Look at this fiddle. I added checking if max is observable and subscribing to it:
if (ko.isObservable(options.max)) {
options.max.subscribe(function(newValue) {
$(element).slider('option', 'max', newValue);
});
options.max = ko.utils.unwrapObservable(options.max);
}
I have a collection of jQUery Ui bindings for KO. I havent done the slider because I havent needed that control in a project. But check my button binding
https://github.com/AndersMalmgren/Knockout.Bindings
ko.bindingHandlers.button = {
initIcon: function (options) {
if (options.icon) {
options.icons = { primary: options.icon };
}
},
init: function (element, valueAccessor) {
var options = ko.utils.unwrapObservable(ko.toJS(valueAccessor())) || {};
ko.bindingHandlers.button.initIcon(options);
ko.utils.domNodeDisposal.addDisposeCallback(element, function () {
$(element).button("destroy");
});
$(element).button(options);
},
update: function (element, valueAccessor) {
var options = ko.toJS(valueAccessor());
ko.bindingHandlers.button.initIcon(options);
if (options) {
$(element).button(options);
}
}
};
The magic is done in the update function, KO will by default subscribe to all observables in a object literal, so if you bind to { max: aObservable } the update function will trigger when any child updates.
I then do ko.toJS(valueAccessor()); to un observify the object and use that to update the jQuery control. This method can be used for slider as well, its generic and you do not need to add extra code for each setting