我想使用 Meteor.setInterval() 来更新时间模板，它不起作用 [英] I want to use Meteor.setInterval() to update a time-template, it doesnt work

问题描述

我想用 Meteor.setInterval 命令更新我的时间函数.

I want to update my time-function with the Meteor.setInterval-command.

这是我的 *.js 文件的样子:

This is how my *.js-file looks like:

function uhrzeit() {
  var zeit = new Date();
  var std = zeit.getHours();
  var min = zeit.getMinutes();
  return std + ":" + min;
};

if (Meteor.isClient) {
  Template.uhr.zeit = function() {
    Meteor.setInterval(uhrzeit, 1000); //Edit: Changed it to pass, not call the function.
    return uhrzeit();
  };
}

模板未更新.它会在我更新页面后显示实际时间，但不会定期更新.或者至少我没有改变 HTML 中的时间.

The template is not updated. It shows me the actual time once I update the page but doesn't update regularly. Or at least I doesnt change the time in HTML.

推荐答案

你的函数不是响应式的.您需要设置一个依赖项，确保您的数据函数依赖它并定期更新它.

Your function is not reactive. You need to set up a dependency, ensure your data function depend on it and update it periodically.

另外，数据函数也不是调用setInterval的好地方.它可以被多次调用并创建许多间隔，这是不受欢迎的.created 更适合处理此类事情.

Also, data function is not a good place to call setInterval. It can be called many times and create many intervals, which is undesired. created is a better place for such things.

此外，请确保清除您创建的所有间隔.destroyed 是这样做的好地方.

Also, make sure to clear all intervals you create. destroyed is a good place to do so.

代码:

if (Meteor.isClient) {

  var zeitDep = new Deps.Dependency(); // !!!
  var zeitValue;
  var zeitInterval;

  function uhrzeit() {
    var zeit = new Date();
    var std = zeit.getHours();
    var min = zeit.getMinutes();
    zeitValue = std + ":" + min;
    zeitDep.changed(); // !!!
  };

  Template.uhr.created = function() {
    uhrzeit(); /* Call it once so that we'll have an initial value */
    zeitInterval = Meteor.setInterval(uhrzeit, 1000);
  };

  Template.uhr.zeit = function() {
    zeitDep.depend(); // !!!
    return zeitValue;
  };

  Template.uhr.destroyed = function() {
    Meteor.clearInterval(zeitInterval);
  };

}

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