javascript - 如何在不触发计算的情况下更新计算中的可观察对象？

Question

我有一个用于许多计算函数的特定 knockout 可观察对象，它的工作方式完全符合预期。但是，在这些计算函数之一上，我不希望它在更新可观察对象时触发。代码明智它看起来像这样:

  self.obs1 = ko.observable(foo);
  self.obs2 = ko.observable(bar);

  //I want this computed to behave normally
  this.comp1 = ko.computed(function() {
    return self.obs1() + self.obs2();
  }, this);

  //I want this computed to trigger on obs1 update but ignore updates to obs2
  this.comp2 = ko.computed(function() {
    return self.obs1() + self.obs2();
  }, self);

  setTimeout(function() {
    self.obs1(20);
    self.obs2(15);    
  }, 1000);

https://jsfiddle.net/r73yLk5u/

请注意，当执行 comp2 时，我仍然需要能够访问 obs2 的当前值，我只是不希望 obs2 的更新触发 comp2 具有新值。

这可能吗？

Answer 1

要使其忽略对可观察对象的更新，请使用 peek(docs):

The peek function lets you access an observable or computed observable without creating a dependency.

更新示例:

//I want this computed to trigger on obs1 update but ignore updates to obs2
  this.comp2 = ko.computed(function() {
    return self.obs1() + self.obs2.peek();
  }, self);

https://jsfiddle.net/r73yLk5u/2/