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  JSON unmarshal in GoLang

In almost all mainstream programming languages, there is either built-in or third-party library to support parse JSON data because it is so popular for organizing and transferring data among different services. In GoLang, the built in json package also provides functions for marshalling and unmarshalling JSON data. Marshalling GoLang struct to a JSON string is relatively simple, just need to call json.Marshal(), it's a bit complicated to unmarshal an arbitrary JSON string into a GoLang struct ob...

   GOLANG,JSON,UNMARSHAL,EMPTY INTERFACE     2019-11-09 21:57:30

  The hidden risk of passing slice as function parameter

In Go's source code or other open source libraries, there are lots of cases where a slice pointer is passed to function instead of slice itself. This brings up a doubt why not passing slice directly as its internal is backed by an array pointer to point to underlying data? For example, in log package, the formatHeader function takes a parameter buf as type *[]byte instead of []byte. func (l *Logger) formatHeader(buf *[]byte, t time.Time, file string, line int) {} Let's understand the r...

   GOLANG,SLICE,SLICE POINTER     2020-12-13 06:11:14

  How to monitor user behavior in webpage

Sometimes there is a need for website owners to monitor user behavior on the site so that they can know what pages are mostly visited and which parts are more popular so that they can provide better service to their users. These behavior usually contain user clicks, user mouse over events etc. These data can be sent back to server when triggered with some meta data. In this post, we will cover a few ways to monitor user behavior on a web portal and send data back to backend sever. 1. Synchronous...

   HTML,BEACON API,PING,USER BEHAVIOR     2019-06-29 06:06:59

  Loading images progressively using Gaussian blur

The popular online publishing platform Medium has adopted an impressive image loading mechanism -- pure color - blur image loading - real image loading. Since images on Medium usually have high definition, it takes much time to load an image and hence brings a bad user experience if rendering the image after it's completely downloaded. The solution Medium comes out is to preload an small image when the real image is being loaded.  On Medium, the HTML code will have below pattern ...

   JAVASCRIPT,ALGORITHM,GAUSSIAN BLUR,MEDIUM,BLUR IMAGE     2016-09-25 03:33:00

  Generate certificate in Java -- Store certificate in KeyStore

In previous post, we have explained how to create a certificate chain in Java. After generating the chain, we need to store it somewhere so that it can be used later when we are doing the actual SSL communication, either in a key store or trust store. This post will show you how to store the private key and its associated certificate chain in a keystore file. There are different types of keystore in Java, in this post, we will choose the JKS to demonstrate how to store the certificate chain. Whe...

   Java,Certificate chain,Keystore     2014-08-20 03:56:39

  Behavior of defer function in named return function

In Go, there is a special concept of named return value in function where a returned value can have name. For example, below is a named function in Go. func returnNamed() (i int) { i = 1 return } When the function returns, the return value i will have a value of 1.  Also, Go has a concept of defer which will execute a function just before the calling function exits. This is similar to what finally block does in other languages such as Java. For example, a defer function can be func deferF...

   GOLANG,DEFER,NAMED RETURN,DIFFERENCE     2018-11-20 09:04:07

  Emacs adventures

I have been using Emacs for over a year now. I actually didn’t learn a lot when I started using it (just the basics to get going and then some relatively common keyboard shortcuts), but lately I have been reading and learning much more about it. I’m so grateful by everything I’ve learned from different people on the net that I wanted to share a couple of things I’ve learned, and a simple major mode for editing AsciiDoc documents. As a long-time VIM user, I f...

   Editor,Linux,Emacx,VIM,Shortcuts     2011-11-30 11:56:49

  A New Experimental Feature: scoped stylesheets

Chromium recently implemented a new feature from HTML5: scoped stylesheets, aka. <style scoped>. A web author can limit style rules to only apply to a part of a page by setting the ‘scoped’ attribute on a <style> element that is the direct child of the root element of the subtree you want the styles to be applied to. This limits the styles to affect just the element that is the parent of the <style> element and all of its descendants. Example Here’s a...

   HTML5,Style,Draw,Use case     2012-03-23 12:11:47

  A mini post on GoLang context

In a GoLang web server, every request coming in will be handled by a goroutine. In the request handler, the logic may also need to create new goroutine to handle other tasks like RPC call. When the request is processed and response is returned, these goroutines created need to be exited so that no goroutine leak should happen. package main import ( "fmt" "log" "net/http" ) func main() { http.HandleFunc("/echo", func(w http.ResponseWriter, r *http.Request) { fmt.Println(&r) w.Write(...

   CONTEXT,GOLANG     2019-12-14 06:21:02

  Let's talk about JSON.stringify()

JSON has been used in lots of places to exchange data among different services/systems. Nowadays all mainstream programming languages have built-in library support of JSON data parse and stringify. In this post, let's talk about JSON.stringify() in JavaScript. Let's first take a small example of Object conversion handling. There is a requirement to convert below object const todayILearn = { _id: 1, content: '今天学习 JSON.stringify()，我很开心！', ...

   JAVASCIPT,JSON,JSON.STRINGIFY     2020-02-22 04:25:08

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