为什么 javascript getMonth 从 0 开始计数，getDate 从 1 开始计数? [英] why does javascript getMonth count from 0 and getDate count from 1?

问题描述

这个问题纯粹是为了满足我的好奇心.

This question is purely to satisfy my curiosity.

在 JavaScript Date 对象中，当您调用 getMonth() 时，它返回月份，但从 0 开始计数.

In the JavaScript Date object, when you call getMonth() it returns the month but it counts from 0.

0 = January
1 = February 
...

但是当你调用 getDate() 时，它从 1 开始计数

But when you call getDate() it starts counting from 1

1 = 1
2 = 2
... 

为什么不一致?

推荐答案

我认为这是因为在名称数组中引用会更容易，即

I assume it's because it would be easier to reference in an array of names, i.e.

var months = ["January", "February", "March", "April", "May", "June", "July",
         "August", "September", "October", "November", "December"];

var d = new Date();

var namedMonth = months[d.getMonth()];

如果getMonth()返回1-12，那么程序员每次想要一个d.getMonth()-1花式命名月份.

If getMonth() returned 1-12, then programmers would have to do d.getMonth()-1 everytime they wanted a fancy named month.

一个月中的几天本身没有特定的名称".getDate() 返回 1-(28-31).我们通常只用他们的号码来称呼他们.

Days of the month don't have specific "names" per se. The getDate() returns 1-(28-31). We usually just refer to them by their number.

与 getMonth() 相同的概念也适用于 getDay()，它根据星期几返回 0-6

The same concept as getMonth() applies for getDay() also, which returns 0-6 based on the day of the week

var days = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];

var namedDay = days[d.getDay()];

所有这些都会返回如下内容:

All this returns something like:

console.log("Month: month[" + d.getMonth() + "]: " + namedMonth); 
//Month: month[3]:  April
console.log("Day: days[" + d.getDay() + "]: " + namedDay); 
// Day: days[4] : Thursday 

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