跟踪淘汰赛中的评估数 [英] track number of evaluations in knockout

问题描述

我想知道如何跟踪下面的GetArray1()和GetArray2()的可剔除可观察数组中的评估数. 我已经阅读了 fiddle链接中的示例，但不确定如何安装它进入这种情况.

I would like to know how to I track the number of evaluation in knockout observable array for GetArray1() and GetArray2() below. I have read a sample from this fiddle link but not sure how to fit it into this situation.

var data1 = [{
    "Hours": 1
}, {
    "Hours": 2
}, {
    "Hours": 3
}];


function ViewModel() {
    var self = this;
    self.sampleArray = ko.observableArray([]);
  
   var newData = ko.mapping.fromJS(data1)();
    self.GetArray = function() {
       ko.utils.arrayForEach(newData, function (item) {
          self.sampleArray.push(item) //push here
       });
    }
    
    self.GetArray2 = function() {
       $.each(newData, function (index, value) {
          self.sampleArray.push(value) //push here
       });
    }
    
    self.GetArray();
  self.GetArray2();
}
ko.applyBindings(new ViewModel())

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout.mapping/2.4.1/knockout.mapping.min.js"></script>

<div data-bind="foreach:sampleArray">
    <p data-bind="text:Hours"></p>
    <br/>
</div>

推荐答案

在您提供的链接中，他们正在使用fn创建函数，该函数具有用于获取re-evaluation计数的计算逻辑

well in the link you provided they are creating a function using fn which has the computation logic for getting the re-evaluation count

更好的方法是使用在computedContext下计算的内置函数isInitial和getDependenciesCount.

Better way would be using inbuilt functions isInitial and getDependenciesCount of computed under computedContext .

逻辑:

 ko.computed(function () {
     var subscribe = self.sampleArray(); //declared on top to subscribe initially
     if (ko.computedContext.isInitial()) return true;
     var count = ko.computedContext.getDependenciesCount();
     self.revaluationCount(self.revaluationCount() + count);
 });

根据文档:

isInitial()—如果在第一次调用时调用此函数，则返回true 曾经评估过当前计算得出的可观察值，或者为false 否则.对于纯计算的可观察物，isInitial()始终为 未定义.

isInitial() — A function that returns true if called during the first ever evaluation of the current computed observable, or false otherwise. For pure computed observables, isInitial() is always undefined.

getDependenciesCount()-返回依赖项的数量 在当前评估过程中，到目前为止已检测到的计算出的可观测值.

getDependenciesCount() — Returns the number of dependencies of the computed observable detected so far during the current evaluation.

在此处查看完整的 文档 .

Check here for complete documentation .

具有完整代码的工作示例 此处

working sample with complete code here

这篇关于跟踪淘汰赛中的评估数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IT屋！