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  JavaScript efficiency catch up

JavaScript is a very flexible language, we can write JavaScript code freely with various styles, different kinds of codes will have different execution efficiency. Here we summarize some tips we get from our development. Efficiency of JavaScript itself JavaScript has execution context chain, closures, prototype inheritance, eval etc. It brings us some magic features, but it also introduces the performance issue, if we don't use them properly, it will affect the codes execution efficiency. 1. Glo...

   JavaScript,efficiency,event delegation,eval     2013-04-02 04:08:46

  Google is returning back to China

It has been five years since Google announced its difficult decision to leave China in 2010. The well known reason was that Google didn't want to conform to China's censorship request on sensitive information. During these five years, many stories happened bbetween these two sides. Things may turn around now as there are a few indications where Google may return back to China at an appropriate time soon. The most convincing indication is that a customized Google play -- Google online shop may a...

   Google,China,Alphabet,Google play     2015-09-06 04:13:30

  What can CSS :has pseudo class be used for?

CSS's :has is a pseudo-class representing an element if any of the selectors passed as parameters matching at least one element. From the name, it's also easy to understand how it matches elements. The syntax is pretty easy as well: :has([some-selector]) With this pseudo class, it can do lots of things which previously would be challenging or need tweaking the DOM elements with JavaScript. This post will demonstrate what :has can be used for. Introduction Below are a few simple ex...

   CSS,:HAS,:NOT,PSEUDO CLASS     2022-09-18 01:40:54

  How to send asynchronous requests in PHP

It’s easy to make asynchronous calls in PHP with just a little bit of HTTP header knowledge and some library code around PHP sockets. This technique is useful when posting requests to your own server for bits of logic you’d like to run in the background.  If you don’t control the endpoint, you might not be comfortable with some of the limitations, such as the inability to read anything from the response.  So, you couldn’t post data to a we...

   PHP,Asynchronous request,socket     2012-04-28 06:45:51

  How does MySQL handle DROP TABLE

A few days ago, when executing DROP TABLE in MySQL, all processes including DDL and DML were hung until DROP TABLE was completed. I am confused about this phenomenon. I have reviewed the source codes of MySQL to check how MySQL internally handle DROP TABLE. When user trigger DROP TABLE command: ########################MySQL SERVER drop table######################## /* Sql_table.cc  delete (drop) tables. */bool mysql_rm_table( )   /*   Execute the drop of a normal or temporary...

   MySQL,DROP TABLE     2012-09-24 11:34:05

  Use DTrace to diagnose gdb issues

A few days ago, I installed the newest 64-bit gdb program (version 7.7.1) on Solaris 10 (X86_64 platform) to debug programs. After playing with the gdb a day, I found 2 issues about gdb:(1) The "set follow-fork-mode child" command doesn't take effect. By default, after the parent process forks the child process, the gdb will track the parent process, so this command can make gdb begin to follow the child process. But this command works OK on Linux.(2) The gdb can't parse the 32-bit application c...

   DTrace, debug, gdb, UNIX     2014-06-28 05:11:20

  What does super.clone() do?

Object class has a protected clone() method declared to make it possible for all classes make a clone of itself when needed. The clone() is often used when a new instance of the class is needed while at the same time to maintain the same state as the original object. Any class which wants to have clone enabled has to implement the marker interface Cloneable. If a class which implements Cloneable doesn't override the Object.clone() method, the Object.clone() method will be called to just make a b...

   Cloneable,super.clone(),clone,Java     2015-01-07 05:25:52

  Mac shortcut key cheatsheet

More and more people are using Mac computers or switch from Windows or other OS to MacOS, there are lots of shortcut keys which can help improve the work efficiency or ease operations. This post will try to list some commonly used shortcut keys in Mac. But before that, let's first know some common keys on a Mac computer keyboard. There are four major function keys: Command, Control, Option and Shift. Most of the shortcut keys will combine the functional key and other key. Basic Command key is t...

   SHORTCUT,SCREENSHOT,COMMAND,SHORTCUT KEY,MACOS     2019-02-05 07:13:06

  Useful Bash Scripts

Many people hack together shell scripts quickly to do simple tasks, but these soon take on a life of their own. Unfortunately shell scripts are full of subtle effects which result in scripts failing in unusual ways. It's possible to write scripts which minimise these problems. In this article, I explain several techniques for writing robust bash scripts. Use set -u ...

   Linux,Shell,Bash,Command,Robust     2012-01-15 10:28:00

  Writing robust shellling scripts

Many people hack together shell scripts quickly to do simple tasks, but these soon take on a life of their own. Unfortunately shell scripts are full of subtle effects which result in scripts failing in unusual ways. It's possible to write scripts which minimise these problems. In this article, I explain several techniques for writing robust bash scripts. Use set -u ...

   Robust,Shell script,Set,Commands     2012-03-19 13:25:26

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