Knockout.js 3.4.0 RC 发布，此版本更新内容如下：
功能增强
#1715 - Add ko.onError handler that provides more consistent error/stack information for async operations and event handlers
#1728 - Include deferred updates functionality in Knockout core
#1738 - Deferred Updates 1 - ko tasks functionality; deferred extender for enabling deferred Updates
#1753 - Deferred Updates 2 - add ability to turn on deferred updates globally by setting ko.options.deferUpdates = true;
#1795 - Deferred Updates 3 - dependency tree scheduling
#1774 - Add ko.options.useOnlyNativeEvents (default false) that can control if KO uses jQuery (if available) for binding events
#1839 - Performance Improvement - for named templates that use a template or normal element use the element directly as the template to clone
#1840 - Performance Improvement - Make observables 2-3x faster to instantiate and reduce memory usage by 50%
#1841 - Performance Improvement - Make computeds 2x faster to instantiate and reduce memory usage by 50%
#1870 - Add ko.isPureComputed.
Bug 修复
#1256 - Better handling when an item is added while a beforeRemove animation is running
#1380 - observableArray sort and reverse methods now return the observableArray rather than the underlying array
#1510 - Do not define a custom element when a component name matches a standard element
#1591 - Make checked binding work properly with writable computed observables
#1613 - IE8 issue with calling .apply with an empty second argument
#1683 - Rearrange code to avoid prototype issue in Opera mobile
#1709 - dontLimitMoves option should be respected when comparing arrays
#1718 - ko.toJS no longer replaces RegExp objects with plain objects
#1756 - Use a hasOwnProperty check when registering components
#1781 - Trim string in default css binding
#1783 - Skip template elements when binding
#1788 - Fix textInput edge case in IE9
#1790 - Remove version from bower.json and don't update it in build
#1794 - Exception in an afterAdd callback should not cause duplicate elements
#1810 - Don't check for require for CommonJS
#1855 - Fix potential memory leak in component binding
#1893 - hasFocus fixes in IE
Knockout 是个JavaScript library，帮助创建丰富的显示和编辑器UI，通过干净的底层数据模型。你可以在任何时候动态更新UI的选择部分。
下载地址：https://github.com/knockout/knockout/archive/v3.4.0rc.zip
来自:开源中国社区
