每隔X秒在KnockoutJS中重新评估计算函数 [英] Reevaluate a computed function every x seconds in KnockoutJS

问题描述

我是否可以每1000毫秒执行一次计算函数，以在UI中每显示1000毫秒获得一个新的时间跨度值?

Can I execute the computed function say every 1000 ms to get a new timespan value every 1000 ms displayed in my UI ?

self.timespan = ko.computed(function() {
        return self.orderTime() + " " + new Date();
});

推荐答案

将您的new Date()包装在可观察的计时器中，并使用

Wrap your new Date() in a timer observable, and update it every 1000 ms using setInterval, for example like this:

function myViewModel() {
    var self = this;

    self.orderTime = ko.observable(new Date(2013,1,1,12,0,0));
    self.timer = ko.observable(new Date());

    self.timespan = ko.computed(function() {
        return self.orderTime() + " " + self.timer();
    });    

    window.setInterval(function() { self.timer(new Date()); }, 1000);
}

ko.applyBindings(new myViewModel());

如果愿意，还可以始终将timer可观察到的内容设为ViewModel范围的私有对象，具体取决于您是否要直接公开它.

If you want you could also always make the timer observable private to the ViewModel's scope, depending on whether you want to expose it directly or not.

有关演示，请参见此小提琴.

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