Whatsapp 網頁版 和 手機的溝通

Whatsapp 網頁版 如何可得到手機的認證?

Whatsapp 網頁提供了QR Code. 用家只需用手機的Whatsapp 掃一掃這個 QR Code 就可以用到 Whatsapp 網頁版。

Whatapp Web Page

究竟Whatsapp 網頁版如何做到呢?

使用Chrome 開啟 Development Tool 的 Network,就會看到有一個 Websocket 的Connection。當用家掃了 QR Code , Whatsapp 網頁版的 Server 就會通知 用家的網頁,啟用 Whatsapp 網頁版。

Whatsapp Page Network

The difference between Canvas and SVG in HTML5

Canvas and SVG

Canvas can be changed once it is painted in browser unless you re-painted it.

SVG is markup language and regarded as a DOM element in browser.


SVG Canvas
High Level (Regards as Objects in DOM) Low Level (Regards as bitmap image)
Standard XML Format by markup syntax Drawable region by Javascript API



It allows GPU accelerated usage of physics and image processing and effects as part of web pages canvas.

It can be seen as enhanced technology to Canvas (HTML5).

From: https://en.wikipedia.org/wiki/WebGL

HTML5 – Storage


In Browser Context, it provide three ways for storing data.

  • Local Storage, a simple key/value persistence system.
  • WebSQL, deprecated relational database.
  • IndexedDB, a NoSQL database


Local Storage

  • a simple key/value persistence system.
  • before HTML5, application data had to store in cookies.
  • more secure and larger storage limit.
  • per domain and protocol. i.e. All page from same domain can access the same data.



  • Basically, SQLite, a light relational database, embedded in browser.
  • Deprecated Specification



  • a NoSQL database, a Javascript-based object-oriented database that object is retrieved by indexed key.



[Deprecated] HTML5: WebSQL

WebSQL is in HTML5 Specification. But it is deprecated by W3C in November 2010. Basically, it is specification that introduces various APIs to manipulate client-side relational database using SQL.

However, not all browser support it. For example, IE does not support it.

Support: Chrome, Opera, Safari


Related SQL Database: Index Database API


Related Reading:

Beyond HTML5: Database APIs and the Road to IndexedDB



HTML5 Overview

It is specification by World Wide Web Consortium (W3C). It has introduced new markup, new APIs that can be called by Javascript, XHTML5.


  • HTML Geolocation
  • HTML Drag and Drop
  • HTML Local Storage
  • HTML Application Cache
  • HTML Web Workers