Knockout makes it easier to create rich, responsive UIs with JavaScript
This release fixes a few regression bugs in 3.5.0:
if option throws an error #2446value binding on <select> when the options are generated via a foreach binding #2452arrayChange notifications when using deferred updates #2454<script> template contents #24843.5.1 also fixes some issues with and expands 3.5.0's TypeScript definitions.
Knockout 3.5.0 includes a few new bindings and new ways to interact with observables and bindings. The full list is detailed under 3.5.0 Beta, 3.5.0 RC, and 3.5.0 RC2.
The final 3.5.0 release includes fixes for a few regressions in the pre-production releases:
if bindings (#2414)foreach and beforeRemove (#2419)foreach and Punches plugin (#2433)foreach and if (#2439)This release includes a number of fixes for regressions in the previous 3.5.0 release candidate. Given the time since the RC, we also decided to include a few small improvements.
foreach binding.style binding to correctly append px.ko.contextFor when used after ko.applyBindingsToNode.ko.utils to use native array methods.createChildContextWithAs option and add noChildContext binding option. The default behavior for as matches previous releases.descendantsComplete and if/ifnot/with bindings.if/ifnot/with bindings: completeOn: "render" will have the binding wait to trigger descendantsComplete until it is rendered.ko.applyBindings throws an error if a non-Node is given as the second parameter.options objects as a parameter to createChildContext.method parameter to the rateLimit extender.style binding.foreach.We decided to keep the more standard return value for ko.utils.arrayFirst, which now returns undefined instead of null when no item matches.
Changes since 3.5.0 Beta:
descendantsComplete to include bindings other than component, such as if, with, etc.ko.when will return a Promise if called without a callback function.Full list of issues: https://github.com/knockout/knockout/milestone/9?closed=1
Important: This release includes some minor breaking changes to the foreach binding to improve performance and clarify features. These changes can be turned off using global options.
When using the as option with the foreach binding, Knockout will set the named value for each item in the array but won't create a child context. In other words, when using as, you will have to use the named value in bindings: text: item.property rather than text: property. This can be controlled by setting ko.options.createChildContextWithAs = true. (See #907)
To improve performance when array changes are from a known, single operation, such as push, the foreach binding no longer filters out destroyed items by default. To turn this off and filter out destroyed items, you can set includeDestroyed: false in the foreach binding or set ko.options.foreachHidesDestroyed = true to use the previous behavior by default. (See #2324)
if and with using the new childrenComplete binding or subscribing to the childrenComplete binding event.
(See #2310)koDescendantsComplete method in the component viewmodel or subscribing to the descendantsComplete binding event. (See #2319)sorted and reversed methods that return a modified copy of the array. This is in contrast to sort and reverse that modify the array itself.class binding supports dynamic class strings. This allows you to use the css and class bindings together to support both methods of setting CSS classes.using binding, similarly to with, binds its descendant elements in the context of the child viewmodel. Unlike with, which re-renders its contents when the viewmodel changes, using will just trigger each descendant binding to update.hidden binding works oppositely to visible.let binding allows you to set values that can be used in all descendant element bindings, regardless of context.let, you can set such values at the root context by providing a function as the third parameter to ko.applyBindings. (See #2024)spectate event whenever their value changes. Unlike the standard change event, this new event isn't necessarily delayed by rate-limiting or deferred updates. You can subscribe to the event without waking a sleeping pure computed; the computed will notify the event if it is accessed with a new value.getDependencies method that returns an array of the observables that the computed is currently watching.attr binding supports namespaced attributes such as xlink:href in svg elements.ko.when function allows you to run code once when an observable or condition becomes true.ko.isObservableArray function can be used to check if something is a ko.observableArray.style binding will use jQuery if present. Even without jQuery, the binding now supports standard style names, such as background-color, and automatically appends px if needed to styles that expect it.<!--/ko-->).30 or so separate fixes are included in this release,
css binding accepts multiple classes in a string and dynamic class names.text binding can be used in virtual elements: <!--ko text: myValue--><!--/ko-->
options binding, it will skip destroyed items (unless optionsIncludeDestroyed is passed as truthy), optionsValue can accept a function just like optionsText, and optionsCaption can be an observable.with binding will bind to the original child DOM elements when its initial value is truthy, and keep a copy of the elements as a template.if and ifnot bindings will bind to the original child DOM elements when the initial value is truthy for if or falsy for ifnot. Additionally, they will only re-render the content when the truthiness of the value changes.attr binding handles the name attribute properly in older versions of IE.peek function for access within a computed without adding a dependency.observableArray mutation functions no longer cause a dependency within a computed.isActive function that indicates that the computed has dependencies (can be triggered again).change (normal manual subscription) and beforeChange callbacks no longer create dependencies.foreach and template enhancementsforeach functionality now does its best to understand items that were moved and move their content rather than re-render them.beforeMove and afterMove callbacks can now be configured when using foreach functionality.foreach and template bindings now accept an as option to give $data an alias.afterRender, beforeRemove, afterAdd, beforeMove, and afterMove callbacks will no longer cause dependencies.ko object is now available from within bindings, even if ko is not global, such as when used with an AMD loader.$element variable.$context variable.This release fixes a number of bugs related to deferred updates and computed observables.
Fixed:
pureComputed sometimes doesn't pick up a change in a dependency (#1975 and #1992)arrayChange events (#1973 and #1974)$rawData within with bindings and rendered templates (#1415)computed._latestValue in debug mode (b3f24b1e247c1b)ko.tasks).ko.onError handler, if defined, for errors from asynchronous code.ko.options.useOnlyNativeEvents can be set to tell Knockout to use only native (not jQuery) events.ko.isPureComputed().The 3.4.0 RC release notes has the full list of issues and pull requests included in this release. The final release fixes two regression bugs found in the RC:
beforeRemove behavior can break retained items.ko.computed.setTimeout. Since microtasks are run before the browser repaints the page, all loaded components will be initialized and displayed in a single repaint. Although this reduces the overall time needed to display components, it could result in a longer delay before anything is displayed.ko.observable and ko.computed no longer use a closure when defining their methods, such as dispose and valueHasMutated. These functions expect this to be set correctly and so can't be used directly as a callback. Instead you'll need to use bind, such as obs.dispose.bind(obs).