The selectors in CSS can easily help us add the required styles to the specified elements. This article provides detailed answers to the three selectors ":nth-child", ":first-child" and ":first-of-type" The difference.

JavaScript is a language that will definitely be used in web development. This article describes in detail how to get the actual line number of the current code at runtime.

JavaScript is a language that will definitely be used in web development, among which null and undefined are often encountered by us. This article describes the characteristics of the two in detail.

When setInterval is running in the background of the browser, the minimum trigger interval will be forcibly changed to 1000 milliseconds, and will stop after running for a period of time. This article describes how to solve this problem.

Insufficient disk space on Linux is usually caused by excessive log files. But we often don't know where the log files are stored. At this point, we need to look at the size of the directory layer by layer to find the location of the file. This article introduces a command on Linux to view the file size of a directory.

When compiling and installing Redis5 on CentOS7, there was an error that jemalloc.h could not be found. This article describes how to solve it.

When compiling and installing Python3, there was an error in the title. This article describes how to solve it.

Diodes are very commonly used electronic components. This article mainly introduces the forward and reverse characteristics of diodes.

When we write code, there will always be frequent errors in some places, and these errors are unavoidable and can be ignored. At this time, we can use PHP's error suppressor to block errors.

Using YUM to install software is much more convenient than compiling and installing. But if our server does not have a public IP in the internal network, we need to connect to the public network through a proxy server. This article describes how to configure a SOCKS5 proxy for YUM.

Apache is the world's most used web server software. It can run on almost all widely used computer platforms. Because of its cross-platform and security is widely used, it is one of the most popular Web server-side software. This article describes in detail how to install Apache on CentOS7.

.NET is a Microsoft development platform, because it can only run on Windows in the early days, it has many limitations. But the new .NET Core already supports running on Linux. This article describes in detail how to install .NET Core on CentOS7.

MySQL is a very commonly used open source relational database. MySQL8 is more rigorous and enhanced security than the previous version. At the same time, MySQL8 has also made many optimizations in performance. This article describes in detail how to install and configure MySQL8 on CentOS7.

SVN is the abbreviation of subversion, which is an open source version control system. It is usually used for multiple people to jointly develop the same project, to achieve shared resources, and ultimately centralized management. This article describes in detail how to install SVN service on CentOS7.

MariaDB is a branch of MySQL. Its usage is basically the same as MySQL, but it supports multi-host clusters, which is different from MySQL's master-slave mode. This article describes in detail how to install MariaDB 10.4 on CentOS7.

If we need to add and subtract dates and times in MySQL, we can use: DATE_ADD, DATE_SUB, ADDDATE, SUBDATE, this article explains the use of these functions in detail.

Usually we need to capture global errors in PHP and then record the logs, so that we can find potential problems in the program in time. But after we set the error callback function with set_error_handler, we still can't catch FATAL level errors. This article describes how to capture FATAL level errors generated during PHP runtime.

EMQX is a very complete MQTT server. This article describes how to create an authorization code to call the API interface of EMQX.

EMQX is an excellent MQTT server. This article describes how to use your own code to control authorization when smart clients connect to services and subscribe to publish topics.

EMQX is an excellent MQTT message server. Its cluster supports tens of millions of connections and has a flexible extension mechanism. This article describes in detail how to install EMQX on CentOS7.