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  Name resolution order in JavaScript

To understand what value a variable has in JavaScript, we need to understand some concepts such as scope and name resolution order. JavaScript has two scopes; one is program level and the other one is function level. Unlike in C,C++ or Java, JavaScript has no block level scope. So a variable defined in a if block will still be available outside. For example, the below example: var foo = 1; function bar() { if (true) { var foo = 10; } alert(foo); } bar(); The alert will display 10 since the ...

   JavaScript,Scope,Name resolution     2013-07-10 01:29:28

  Java Polymorphism and Overriding Methods

Most Java developers will be familiar with polymorphism – we’ve all seen the example of the Dog and Cat classes inheriting from some abstract Animal class and having their say() methods produce different results. But it’s still worthwhile to look at a few simple examples to reinforce the concepts.First, we define a simple class with one instance method and one static method.public class A { public String getName() { return "I a...

   Java,Overriding,Polymorphism,Demo,Dynami     2011-10-04 14:09:06

  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

  Break down defer statements in GoLang

Basic Concepts What are the characteristics of the deferred statement defer in Go language? When is it usually used? The deferred statement(defer statement) in Go language has the following characteristics: Deferred Execution: Deferred statements are executed before the function containing them exits, regardless of whether the function returns normally or encounters an exception. Last In, First Out (LIFO): If there are multiple deferred statements, they are executed in the order of last in, f...

   DEFER,GOLANG     2024-02-10 21:56:10

  What is good design?

Some quotes about good design from a Germany designer Dieter Rams in documentary "Objectified": Good design should be innovative Good design should make a product useful Good design is aesthetic design Good design will make a product understandable Good design is honest Good design is unobtrusive Good design is long-lived Good design is consistent in every detail Good design is environmentally friendly Good design is as little design as possible This brings up a question -- what...

   METRO,SIMPLICITY,GOOD DESIGN,PRINCIOPLE,UNIX PHILOSOPHY     2012-05-09 06:48:11

  Deep Understanding of ReentrantLock: Unlocking the Mysteries of Java Concurrent Programming

ReentrantLock introduction ReentrantLock is a class in the Java concurrent package, java.util.concurrent.locks, and is an implementation of the Lock interface. As its name suggests, it is a reentrant mutual exclusion lock. A mutual exclusion lock is a synchronization tool used to protect shared resources, ensuring that only one thread can access the resource at a given time. Reentrant means that a thread can acquire the same lock multiple times without causing a deadlock. This lock provides some...

   JAVA,REENTRANTLOCK,CONCURRENCY,MULTITHREADING     2023-05-22 08:01:13

  How to be an excellent programmer

To use a programming language is very easy for a programmer, but it's a dream for many programmers to be an expert software developer. There are five levels of programmers: Novice, Senior novice, competent, proficient, and expert. Most programmers are senior novice. And programmer living in this level are a lot of people who have 1 to 10 years work experience.As a programmer, how to find the bottlenecks for your improvement and how to improve yourself quickly? This is really not an easy question...

   Programming,Tips,Habit     2013-03-26 09:53:38

  Add Sublime Text to your context menu on right click

When opening a text file, you may be used to right click on the file to be opened and then choose the application which can open the file from the context menu. On the context menu, you may see a menu item like "Edit with Notepad++". Nowadays many people especially programmers like to use Sublime Text, but by default this application will not show on the context menu when you right click on a file. There is now frequent request to add this application to the context menu. Here we show a simple b...

   SUBLIME TEXT,CONTEXT MENU,WINDOWS     2015-10-19 08:51:25

  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

  Build Hadoop environment in Linux

Hadoop standalone installation: 1. Install JDK Install JDK with below command: sudo apt-get install sun-java6-jdk Configure Java environment, open /etc/profile, add below contents: export JAVA_HOME = （Java installation directory） export CLASSPATH =".:$JAVA_HOME/lib:$CLASSPATH" export PATH = "$JAVA_HOME/:PATH" Verify installation of Java Type java --version, if it outputs Java version information, then Java is successfully installed. 2. Install SSH Install SSH with below command: sudo ...

   Hadoop.Linux,Configuration     2013-07-31 23:22:27

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