在 Node.js 中设置计时器
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Setting a timer in Node.js
提问by Amanda G
I need to run code in Node.js every 24 hours. I came across a function called setTimeout. Below is my code snippet
我需要每 24 小时在 Node.js 中运行一次代码。我遇到了一个名为setTimeout. 下面是我的代码片段
var et = require('elementtree');
var XML = et.XML;
var ElementTree = et.ElementTree;
var element = et.Element;
var subElement = et.SubElement;
var data='<?xml version="1.0"?><entries><entry><TenantId>12345</TenantId><ServiceName>MaaS</ServiceName><ResourceID>enAAAA</ResourceID><UsageID>550e8400-e29b-41d4-a716-446655440000</UsageID><EventType>create</EventType><category term="monitoring.entity.create"/><DataCenter>global</DataCenter><Region>global</Region><StartTime>Sun Apr 29 2012 16:37:32 GMT-0700 (PDT)</StartTime><ResourceName>entity</ResourceName></entry><entry><TenantId>44445</TenantId><ServiceName>MaaS</ServiceName><ResourceID>enAAAA</ResourceID><UsageID>550e8400-e29b-41d4-a716-fffffffff000</UsageID><EventType>update</EventType><category term="monitoring.entity.update"/><DataCenter>global</DataCenter><Region>global</Region><StartTime>Sun Apr 29 2012 16:40:32 GMT-0700 (PDT)</StartTime><ResourceName>entity</ResourceName></entry></entries>'
etree = et.parse(data);
var t = process.hrtime();
// [ 1800216, 927643717 ]
setTimeout(function () {
t = process.hrtime(t);
// [ 1, 6962306 ]
console.log(etree.findall('./entry/TenantId').length); // 2
console.log('benchmark took %d seconds and %d nanoseconds', t[0], t[1]);
//benchmark took 1 seconds and 6962306 nanoseconds
},1000);
I want to run the above code once per hour and parse the data. For my reference I had used one second as the timer value. Any idea how to proceed will be much helpful.
我想每小时运行一次上述代码并解析数据。作为参考，我使用了 1 秒作为计时器值。任何想法如何进行将非常有帮助。
回答by Marc Fischer
There are basically three ways to go
基本上有三种方式
setInterval()
setInterval()
The setTimeout(f, n)function waits n milliseconds and calls function f.
The setInterval(f, n)function calls fevery nmilliseconds.
该setTimeout(f, n)函数等待 n 毫秒并调用 function f。该setInterval(f, n)函数f每n毫秒调用一次。
setInterval(function(){
console.log('test');
}, 60 * 60 * 1000);
This prints testevery hour. You could just throw your code (except the require statements) into a setInterval(). However, that seems kind of ugly to me. I'd rather go with:
这test每小时打印一次。您可以将代码（除了 require 语句）放入setInterval(). 然而，这对我来说似乎有点丑陋。我宁愿去：
Scheduled Tasks Most operating systems have a way of sheduling tasks. On Windows this is called "Scheduled Tasks" on Linux look for cron.
Use a libaryAs I realized while answering, one could even see this as a duplicate of that question.
