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  Three ways to define class in JavaScript

In object oriented programming, class is the template of object, it defines the properties and methods of a group of objects. Unfortunately, JavaScript doesn't support class, but we can have some workarounds to simulate class.1. Constructor functionThis is the classical approach, it is also the approach mentioned in many text books. It uses the constructor function to simulate class and it uses the keyword this to represent the object internally.function Cat() {  this.name = "Kelly";}when cr...

9,901 0          JAVASCRIPT METHOD CLASS INHERITANCE PRIVATE


  Regular expression to get html meta description

When we need to process a HTML page source code, we often need to retrieve the meta description of the page besides the links in the page. This description is usually located in <meta> tag of a HTML page. The meta description is very useful for search engine index. How can we retrieve the meta description? If we use a regular expression, we can easily get the meta description. In JavaScript, the regular expression looks like : var pattern = /<meta.*?name="description".*?content="(.*?)"....

7,732 0          JAVASCRIPT HTML REGULAR EXPRESSION META DESCRIPTION


  jQuery 2.0 will drop support for some IE6/7/8 oddities

jQuery official website releases its road map for the future jQuery development. This road map reveals that jQuery 1.8 will be released within a month and other consecutive versions will follow the following release plan:jQuery 1.9 (early 2013): many of the interfaces already deprecated in version 1.8 will be removed; some of them will be available as plugins or alternative APIs supported by the jQuery project. IE 6/7/8 will be supported as today.jQuery 1.9.x (ongoing in 2013 and beyond): This v...

3,030 0          JQUERY JQUERY 2.0 IE SUPPORT


  Commonly used AJAX frameworks

Have you ever wondered to design your website like desktop applications? Fortunately, with AJAX we can achieve this. By using AJAX, we no need to refresh the whole page when we just want to update a portion of a website such as the weather information or news panel. This makes our web apps look like desktop applications and bring good user experience to our visitors. You can create an XMLHttpRequest object every time when you want to initialize an AJAX call, unfortunately you may need repeat eve...

3,428 0          AJAX JQUERY FRAMEWORK DOJO YUI


  Update parent window after closing the window opened by window.open()

Imagine we have a webpage which has a text field to let user enter a date. Usually, we may create a calendar window to ask the user to pick one date from the calendar window, when the date is picked, the calendar window will close and the date picked will be put into the text field. This way involves the window.open() method in JavaScript, and we may think how the opened window knows its parent window and then updates the parent window. I give a simple demo on this.We have two pages, on is the p...

5,109 0          UPDATE WINDOW.OPEN JAVASCRIPT RETURN VALUE


  Get hostname from a URL using JavaScript

Sometimes we may have strings which contain some UR;s and we may want to retrieve the hostname from the URLs for some statistic use. For example, we may have a URL : http://www.example.com/aboutus.html. We may want to retrieve the www.example.com from the URL. How? Use regular expression. Here I give an example using JavaScript. If you want to check whether a string is a URL or not. Refer to Detect URLs in a Block of Text. In JavaScript, we can have a regular expression like var pattern=/(.+:\/\...

10,240 0          JAVASCRIPT REGULAR EXPRESSION URL HOSTNAME


  var in JavaScript

Geoff published an article sometime ago--"How one missing var ruined our launch". This article described one case where MelonCard uses Node.js as their backend system, suddenly there was a small registration peak period--50-100 people registered concurrently, then the entire website stopped responding and many other strange problems showed up. When they were investigating the source of the problem, they found one missing var in the following code.app.all(‘/apps/:user_id/status’, function(req...

2,240 0          JAVASCRIPT VARIABLE SCOPE


  Create namespace in JavaScript

A namespace (sometimes also called a name scope) is an abstract container or environment created to hold a logical grouping of unique identifiers or symbols (i.e., names). An identifier defined in a namespace is associated only with that namespace. The same identifier can be independently defined in multiple namespaces. That is, the meaning associated with an identifier defined in one namespace may or may not have the same meaning as the same identifier defined in another namespace. Languag...

4,472 0          JAVASCRIPT EXAMPLE NAMESPACE