Knockout.js中的自定义油门扩展

此外，您的小提琴中有一个错字:self.restrictChangeSpeedComputedVar1 = ko.computed(this.var1).extend({restictChangeSpeed:1000});您拼错了扩展名(restict而不是restrict)，这使我在测试添加的更改时抓狂了，直到发现它为止.关于我的更改的唯一有趣的事情是，现在有人可以向您的计算对象写入内容，但是只要底层计算对象发生更改，它就会始终更新，而我看不到您为何有意尝试写入它.I have an observable that's binded to some input, and sometimes it's value changes too fast, so that the end user does not have time to read it. So I want to restrict the speed of changes in input.But it's not a throttle, because throttle is a bottle neck, and the throttled observable does not change at all while it changes. I want to have a custom throttle, so that the first change applies immediately, and then it might change only after a delay (and of course, each time after a delay it shows the CURRENT value).So far I've written the custom restrictSpeedChange extender. Here it is: http://jsfiddle.net/kasheftin/Pn9r8/4/. And it actually works for usual observables.ko.extenders.restrictChangeSpeed = function(target,timeout) { var writeTimeoutInstance = null; var currentValue = target(); var updateValueAgain = false; return ko.dependentObservable({ read: target, write: function(value) { var updateValue = function(value) { target(value); if (!writeTimeoutInstance) { writeTimeoutInstance = setTimeout(function() { writeTimeoutInstance = null; if (updateValueAgain) { updateValueAgain = false; updateValue(currentValue); } },timeout); } } currentValue = value; if (!writeTimeoutInstance) updateValue(currentValue); else updateValueAgain = true; } });}The problem is I want it to work with computed observables as well. For them throttle extender has throttleEvaluation variable, this variable is used in dependentObservable.js evaluatePossiblyAsync method. But I don't want to change anything in core knockout files.In my example http://jsfiddle.net/kasheftin/Pn9r8/4/ usual observable variable is restrictChangeSpeedVar1 and it works as expected. Computed variable is restrictChangeSpeedComputedVar1. What should I do to make it work like the first one? 解决方案 A quick thought going with your existing code:In your extender, you could see if you are dealing with a non-writeable computed observable, then return an observable that has gone through your extender and has subscribed to the computed.ko.extenders.restrictChangeSpeed = function(target, timeout) { var writeTimeoutInstance = null; var currentValue = target(); var updateValueAgain = false; var interceptor; if (ko.isComputed(target) && !ko.isWriteableObservable(target)) { interceptor = ko.observable().extend({ restrictChangeSpeed: timeout }); target.subscribe(interceptor); return interceptor; }....The key is that you need something to go through your "write" logic. With a normal computed, it would just re-evaluate its "read" logic and update, never going through your "write" code.Here is a sample: http://jsfiddle.net/rniemeyer/GPbrR/Also, you had a typo in your fiddle:self.restrictChangeSpeedComputedVar1 = ko.computed(this.var1).extend({restictChangeSpeed:1000});You had misspelled your extender name (restict instead of restrict), which made me scratch my head while testing the changes that I added, until I noticed it.The only interesting thing about my changes is that now someone could potentially write to your computed, but it would always update whenever the underlying computed changed and I don't see why you would intentionally try to write to it. 这篇关于Knockout.js中的自定义油门扩展的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！