


As we all know, time type data in PHP can be directly converted into timestamps. In front-end script js, there is also a way to achieve this, which is valueOf()
For example, we can use this code to output the timestamp of the current time point
So what is a timestamp?
The timestamp is all the seconds from 0:00:00 on January 1, 1970 to the current time point. 1970.1.1 0:0:0 This time is the so-called "time epoch" in IT. I believe you have seen it in many articles. For example, Oracle time display, time calculation in Unix and Linux systems, etc. Then why choose 1970 instead of 1900? Let us explain its origin next.
1. When 32-bit computers just started to emerge,
The maximum value that the so-called integer type data can represent is:
System.out.println(Integer.MAX_VALUE);
2147483647
2. The total number of seconds of 365 in a year is 31536000,
3. Divide the two, 2147483647/31536000=68.1,
4. In other words, in the context of 32 bits, the maximum value that can be expressed The long-term interval is 68 years
5. If you count from 1970, it can be said that the maximum time will be reached at 03:14:07 on January 19, 2038,
6. After this time point, The time of all 32-bit operating systems will become 10000000 00000000 00000000 00000000
which is 20:45:52 on December 13, 1901. This will cause time regression, and some software may have major abnormalities.
To summarize the above points, the people who came up with this set of things were actually those who were playing with UNIX at the earliest. They considered that 68 years is not that long, so they started counting these 68 years from 1970. Their hopes Yes, during these 68 years, those who came later could come up with a better mechanism as soon as possible to change this restriction. . . Sure enough, the rise of 64-bit has changed this "end of time" from
January 19, 2038, 03:14:07 - " 292,277,026,596 December 4, 15:30:08
So, this If the number is big enough, the "end of the world" of computer time will really be the end of the world
Code changes the world, my "Source Code", my world!

去掉重复并排序的方法:1、使用“Array.from(new Set(arr))”或者“[…new Set(arr)]”语句,去掉数组中的重复元素,返回去重后的新数组;2、利用sort()对去重数组进行排序,语法“去重数组.sort()”。

本篇文章给大家带来了关于JavaScript的相关知识,其中主要介绍了关于Symbol类型、隐藏属性及全局注册表的相关问题,包括了Symbol类型的描述、Symbol不会隐式转字符串等问题,下面一起来看一下,希望对大家有帮助。

怎么制作文字轮播与图片轮播?大家第一想到的是不是利用js,其实利用纯CSS也能实现文字轮播与图片轮播,下面来看看实现方法,希望对大家有所帮助!

本篇文章给大家带来了关于JavaScript的相关知识,其中主要介绍了关于对象的构造函数和new操作符,构造函数是所有对象的成员方法中,最早被调用的那个,下面一起来看一下吧,希望对大家有帮助。

方法:1、利用“点击元素对象.unbind("click");”方法,该方法可以移除被选元素的事件处理程序;2、利用“点击元素对象.off("click");”方法,该方法可以移除通过on()方法添加的事件处理程序。

本篇文章给大家带来了关于JavaScript的相关知识,其中主要介绍了关于面向对象的相关问题,包括了属性描述符、数据描述符、存取描述符等等内容,下面一起来看一下,希望对大家有帮助。

foreach不是es6的方法。foreach是es3中一个遍历数组的方法,可以调用数组的每个元素,并将元素传给回调函数进行处理,语法“array.forEach(function(当前元素,索引,数组){...})”;该方法不处理空数组。

本篇文章给大家带来了关于JavaScript的相关知识,其中主要介绍了关于BOM操作的相关问题,包括了window对象的常见事件、JavaScript执行机制等等相关内容,下面一起来看一下,希望对大家有帮助。


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