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  Understand GoLang WaitGroup internals and how it works

Background Before getting into the main content, let me give a brief introduction to WaitGroup and its related background knowledge. Here, the focus is on the basic usage of WaitGroup and the fundamental knowledge of system semaphores. For those who are familiar with these, you can skip this section directly. WaitGroup WaitGroup is one of the most common concurrency control techniques in Golang, and its function can be roughly compared to the join() in concurrency control of other languages' mul...

   GOLANG,WAITGROUP,SOURCE CODE     2023-04-26 08:02:01

  Use downcase! with caution in Ruby

Ruby provides ! to change state of some object in place. Hence if you see some functions have ! appended, it means the state of the caller of the function is expected to be changed. This is a very interesting Ruby feature. But sometimes one should be cautious when using this kind of functions because you would get unexpected behavior if using improperly. Let's take an example of String#downcase!. According to the documentation. Downcases the contents of str, returning nil if...

   RUBY,EXCLAMATION MARK,DOWNCASE     2017-02-10 06:34:44

  How to maintain a software project?

For a software engineer, at least from my own experience, maintaining an existing software project would take up a considerable amount of time: adding new features, fixing tricky bugs, and so on. In this post, I will share some some tips about how to become a veteran from a novice quickly when facing a new project. (1) Get familiar with the background knowledge of the project. Every software has its own purposes and users: a device driver serves the specified hardware, whilst a SMS gateway helps...

       2017-08-05 02:20:46

  Why exception would be thrown when deleting element while looping through HashMap in Java

HashMap and other Collection types are frequently used in Java application programming. This post will explain why exception would be thrown when deleting element with Map.remove() while looping through a Map using Iterator. This issue would also occur to other Collection types such as Set, List. Below is a sample code snippet demonstrating the exception thrown. Map<String,String> map = Collections.synchronizedMap(new TreeMap<String,String>()); map.put("key1","value1"); map.put("ke...

   JAVA,HASHMAP,CONCURRENTMODIFICATIONEXCEPTION     2018-06-30 12:49:09

  Shortcut keys in Sublime Text 3(Animated demo)

Sublime Text 3 is a light weight code editor which supports lots of languages. It has lots of shortcuts and plugins easing work of programmers. In this post, we will introduce some shortcuts supported in Sublime Text 3 and show how powerful they are. 1. Select sibling matching(equal) word (Ctrl + D) Put the cursor on one word, press Ctrl + D to select the word, then press Ctrl and following by pressing D, it will select next matching word. The number of Ds pressed will mean number of matching wo...

   TIPS,SHORTCUT KEY,SUBLIME TEXT     2016-04-28 02:41:28

  Web Security: In-Depth Explanation of X-XSS-Protection

What is X-XSS-Protection X-XSS-Protection is an HTTP response header designed to enable or configure built-in cross-site scripting (XSS) filters in certain versions of Internet Explorer, Chrome, and Safari. The purpose of these filters is to detect reflected XSS attacks in the response and prevent the loading of pages, thereby protecting users from such attacks. The X-XSS-Protection response header was initially introduced by Microsoft in Internet Explorer 8 to control the browser's XSS filter. ...

   X-XSS-PROTECTION,WEB SECURITY,CONTENT SECURITY POLICY,XSS,CSP     2023-11-29 01:48:40

  Let's talk about JavaScript deep clone

In JavaScript, deep clone means creating a brand new object that includes all nested objects, with all properties being completely independent copies. This is different from shallow copying, which only copies the first-level properties, with nested objects being referenced rather than copied. There are multiple ways to perform deep copying in JavaScript, but the best one to use depends on the specific use case. Can use JSON.parse & JSON.stringify? ❌ JSON.parse(JSON.stringify(obj)) is a dep...

   JAVASCRIPT,DEEP CLONE     2023-02-25 08:57:11

  How deep should unit test go?

There is a question on Stackoverflow which says "How deep are your unit tests?". It is asked by a guy named John Nolan. The question is not too new, but what catches me is the Best Answer given by Kent Beck, who is the creator of Extreme programming(XP) and Test Driven Development(TDD). Let's look at the question first. The thing I've found about TDD is that its takes time to get your tests set up and being naturally lazy I always want to write as little code as possible. The first thing I seem ...

   Unit test,TDD,XP     2012-09-03 10:11:27

  Let browser prompt for storing password when doing AJAX login

In Web 2.0 era, more and more web applications are using AJAX to replace the traditional HTML form element to perform user login. This usually provides a better user experience than form submission. But it also brings a side effect to the end users. That is the browser will not prompt the user whether s/he wants to save the password so that s/he no needs to enter the username/password again when visiting the same site next time. Below is the code snippet which does the AJAX login.  <scri...

   AJAX,Browser,Login,Password     2015-06-04 10:02:46

  Understanding JavaScript closure and where it can be used

Closure The official definition of closure is: an expression (usually a function) that has many variables and is bound to an environment that includes those variables. In JavaScript, closure refers to the ability of a function to access the lexical scope in which it was defined, even after the function has been executed and left that scope. This ability is due to the fact that when a function is created, it generates a closure that includes a reference to the definition environment of the curr...

   CLOSURE,JAVASCRIPT,USAGE     2023-03-05 02:17:08

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