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  The Strange Behavior of the void Type in TypeScript

Preface In TypeScript (TS), there is a type called void. It represents "nothing" but it's important to note that it's not the same as "nothing" in JavaScript(JS). Typically, void is used to declare the return type of functions. Although you can declare a variable as void, we generally don't do this because it serves no meaningful purpose. Let's explore why in the examples below. The void Type Declaring a Variable as void let name: void; // Declare a variable `name` with type `void`. name = 'nan...

   TYPESCRIPT,JAVASCRIPT,VOID,TYPE     2024-09-13 23:44:26

  Reset submodule to checkout state in git

Sometimes there would be a submodule or some submodules within one git repository, in some cases the submodule may be out of sync with the checkout state as some files in submodule may be changed unexpectedly. How to reset the submodule to be the same as the original checkout state? Let's take an example that we have a git repository A and there is a submodule called ruby-gems under it. Assuming the submodule at remote origin has commit a. And on our local environment, the repository A has a la...

   GIT RESET,GIT SUBMODULE     2020-09-05 08:30:57

  One Way to Quickly Locate SQL with High CPU Usage in MySQL

When the CPU usage of a MySQL database rises abnormally, it's necessary to quickly identify the problematic SQL statements. In this post, we try to provide one way to achieve this.  Below are the actual steps. 1. Use the top command to find the threads with the highest CPU usage in the MySQL process. # Find the MySQL process ID ps -ef | grep mysql # Use the process ID to find the thread IDs with the highest CPU usage: top -H -p In top, press P to sort by CPU usage. Note the thread ID, fo...

   MYSQL,DEBUG,HIGH CPU,SLOW QUERY     2024-08-01 21:25:48

  Ways to check existence of JavaScript object

The design of JavaScript is not so sophisticated. It's very easy for us to make mistakes if we are not very careful when using JavaScript. For example, to check the existence of JavaScript object. Now we want to check whether a global object myObj exists or not, if it doesn't exist, we declare it. The pseudo code for this is : if(myObj not exist){ declare myObj; } You may think it's very easy to write the code. In fact, it is much more difficult than we may think. Juriy Zaytsev says there are m...

   JAVASCRIPT,OBJECT,EXISTENCE     2020-09-12 02:14:02

  PHP Apache MySQL Set-up Note

With the emergence of WAMP, LAMP, PHP developers are liberated from the tedious work of setting up PHP environment. Since PHP, Apache and MySQL are so tightly bundled, WAMP and LAMP provide a setp solution for setting up a PHP environment which includes the programming programming environment, server and database. But for a PHP who wants to learn more, you have to try to set the PHP environment yourself by installing PHP, Apache and MySQL manually and configuring them. Below is a simple note on ...

   PHP,Apache,MySQL     2014-04-07 01:56:43

  GoLang to build smaller executable file

Normally the executable file built with go is a bit large, it is always desired that a smaller executable file should be generated though. In this post, a couple of ways to reduce the size of the executable will be introduced. The end effect is that the executable file size would be much less than the normal generated one. The file which is built normally has below size. Mode LastWriteTime Length Name ---- ------------- ------ ---- -a---- 12/14...

   GOLANG,EXECUTABLE     2019-12-13 20:10:45

  Simple tutorial on git cherry-pick

It is a common operation to move code from one branch to another branch in a multi-branch git repository. Normally there are two scenarios: Want to move all changes in one branch to another branch, now it's called git merge  Want to move only some change/changes from one branch to another branch, now it's called git cherry-pick Usage The purpose of git cherry-pick is to apply some change from one branch to another branch.  git cherry-pick [commitHash] The above command is to app...

   GIT,GIT CHERRY-PICK,TUTORIAL     2020-05-02 00:02:58

  Fix issue docker-credential-desktop not installed or not available in PATH on Mac

Sometimes you may encounter below issue while running docker-compose on MacOS. Traceback (most recent call last): File "docker-compose", line 6, in <module> File "compose/cli/main.py", line 71, in main File "compose/cli/main.py", line 127, in perform_command File "compose/cli/main.py", line 1085, in up File "compose/cli/main.py", line 1081, in up File "compose/project.py", line 527, in up File "compose/service.py", line 354, in ensure_image_exists File "compose/service.py",...

   MACOS,DOCKER,DOCKER-COMPOSE     2020-06-23 03:25:16

  New HTTP status code: 451 Unavailable for Legal Reasons

On June 11th,2012, Google proposed a new HTTP status code to indicate webpage contents which are not conform to law. The new HTTP status code is 451 Unavailable for Legal Reasons. Google Android Developer Advocate Tim Bray submitted the draft for the new HTTP status code, it will be used on some webpages which can not be served because of legal reasons. Visitors will know that the page cannot be seen because of the government censorship.According to the draft, responses using this status code sh...

   HTTP status,451,Tim Bray     2012-06-12 09:07:44

  Push docker image to remote AWS ECR

With the popularity of distributed and large-scale systems, there are more and more adoptions of cloud services. One of the most popular container in the market is Docker and one of the most popular cloud service provider is AWS. From development perspective, there is frequent need to push local docker image to remote ECR for debugging or testing purpose. Normally when a code change is done and the committed change would go through a series of process like code review, push to remote repo, merge...

   CLOUD,AWS,DOCKER,AWS ECR     2020-12-13 04:12:26

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