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  JavaScript to scroll element into view

In AJAX applications, there are frequent needs to scroll some element into view after some modification to the page. For example, after adding an item or updating an element in an admin panel, the page may need to be scrolled to the item added or updated so that we can see the changes immediately. In these cases, JavaScript can be used to scroll the element we want to show. In Vanilla JavaScript, there is no built-in function which can achieve scroll_element_into_view(), but most of modern brows...

   JAVASCRIPT,JQUERY,SCROLLTO,HOW-TO     2015-12-17 03:47:32

  Save QWidget as image

Qt library is an excellent GUI library for C++ programmers developed by Nokia and now is an open source project. Often, we may use QPainter to draw strings, lines or images on a QWidget. We can override the QWidget's paintEvent() method when we want to use QPianter object to draw something on a QWidget. If we want to save the items drawn on QWidget as image for later reference, what can we do? We can save a QWidget as an image. Here is the code for achieving this: QPixmap pixmap(this->size())...

   Qt,C++,QWidget,Image     2012-08-19 12:01:18

  The basics of Client/Server socket programming

  While Client/Server communication model is ubiquitous nowadays, most of them involve socket programming knowledge. In this post, I will introduce some rudimentary aspects of it: (1) Short/Long-lived TCP connection.Short-lived TCP connection refers to following pattern: Client creates a connection to server; send message, then close the connection. If Client wants to transmit information again, repeat the above steps. Because establishing and destroying TCP s...

       2017-09-26 19:43:10

  25 worst passwords in 2012

Weak password is a serious security vulnerability, but the majority of network users still use some universal simple character sequences as the password. SplashData recently announced the world's worst password list in 2012.  "password","123456" and "12345678" are still at top places, while others have varying,  some new passwords like  "welcome" "Jesus" "ninja","mustang"and "password1 "are in the list. With the risk of password loss, SplashData CEO Morgan Slain said we hoped netw...

   Password,Security     2012-10-25 12:04:49

  Why TCP needs 3 handshakes

Prerequisite Knowledge First, let's look at the control bits and state machine of TCP, which form the basis for understanding the three-way handshake of TCP. TCP Packet Control Bits The control bits in the TCP packet header are used to control the status of the TCP connection and can indicate various control information such as connection establishment, termination, reset, etc. There are six common control bits: SYN (Synchronize Sequence Numbers): Requests to establish a connection (part of the...

   REASON,NETWORK,TCP,EXPLANATION,HANDSHAKE     2024-09-28 08:57:52

  Big file transfer in Linux

It's very common that we need to transfer files between two different hosts such as backups. It is also an very simple task, we can use scp or rsync to complete the task well. But what if the file is very big, it may take some time to transfer it. How can we transfer a big file with high speed? Here we propose one solution. Copy file If we copy one uncompressed file, then we should follow below steps: Compress data Send it to another host Uncompress the data Verify the data integrity This will...

   Linux, SCP,ZIP     2013-01-10 05:55:50

  Advantages and disadvantages of GoLang

GoLang is a strong typed language which means it is less flexible than interpreted languages by nature. But Go provides Any type(interface) and Reflect mechanism which make the language very close to interpreted languages on flexibility. More and more people start to learn GoLang. This post is mainly for listing down some of the advantages and disadvantages of GoLang. Advantages Performance(Machine code) GoLang is a compilation language which can be compiled to machine code and the compiled bina...

   GENERICS,GOROUTINE,GOLANG,DISADVANTAGE,ADVANTAGE     2018-11-10 20:46:45

  Understanding How is Data Stored in RDBMS

We all know that DBMS (database management system) is used to store (a massive amount of) data. However, have you ever wondered how is data stored in DBMS? In this post, we will focus on data storage in RDBMS, the most traditional relational database systems. Physical Storage Data can be stored in many different kinds of medium or devices, from the fastest but costy registers to the slow but cheap hard drives, or even magnetic tapes. Nowadays, IaaS providers such as AWS...

   RDBMS,DATABASE     2019-02-04 09:25:36

  LESS/SASS/Stylus development tools summary

LESS,SASS and Stylus are more and more popular among developers. More and more people are using these three tools now. Here we introduce some development and testing tools which can make our development process simpler. SublimeText Many front-end developers are now using Sublime Text 2 as their main text editor, there are many plugins in Sublime Text as well. We can use Ctrl+Shift+P –> install package to search relative plugins. Less Sublime Less build Sublime Less2css Less snippets Su...

   LESS,SASS,Stylus,CSS     2013-02-23 22:45:02

  Use pdb to help understand python program

  As I have mentioned in Why do I need a debugger?: (3) Debugger is a good tool to help you understand code. So when I come across difficulty to understand vfscount.py code in bcc project, I know it is time to resort to pdb, python's debugger, to help me. The thing which confuses me is here: counts = b.get_table("counts") for k, v in sorted(counts.items(), key=lambda counts: counts[1].value): print("%-16x %-26s %8d" % (k.ip, b.ksym(k.ip), v.val...

       2017-08-22 22:42:37

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