Category: Programming

Calling a function of the opener window

Posted: 2006-07-27   |   Categories: JavaScript, Programming

It is possible, using JavaScript, to call a function pertaining to the opener window, that is the window that, calling window.open, opened the current window. The code to use is the following:

  
if (window.opener) {
  window.close();
  window.opener.foo("bar");
}

First it checks if the opener window is still open. In this case, it closes the current window and call the foo function on the opener window.

Creating a Class definition in JavaScript

Posted: 2006-07-24   |   Categories: JavaScript, Programming   |   Tags: Class

There are different ways to define classes in JavaScript. However, this is the most widely used and accepted at the moment:

   
//class
function Person(sLastName, sFirstName, iAge) {
  this.lastName = sLastName;
  this.firstName = sFirstName;
  this.age = iAge;
  this.phoneNumbers = new Array();
}

//method
Person.prototype.showFullName = function() {
  alert(this.lastName + " " + this.firstName);
};

//instances
var oPerson1 = new Person("Lacava", "Alessandro", 30);
var oPerson2 = new Person("Brown", "John", 50);
oPerson1.phoneNumbers.push("1234567");
oPerson2.phoneNumbers.push("7654321");

oPerson1.showFullName(); //outputs Lacava Alessandro
alert(oPerson1.phoneNumbers); //outputs 1234567
oPerson2.showFullName(); //outputs Brown John
alert(oPerson2.phoneNumbers); //outputs 7654321

How to force one or more metacharacters to be treated as ordinary characters in a Java Regular Expression (RegEx)

Posted: 2006-07-12   |   Categories: Java, Programming   |   Tags: Metacharacter, RegExp

When using RegEx in Java you might face the need of treating one or more metacharacters as ordinary characters. As a reminder the metacharacters in a Java RegEx are:

([{^$|)?*+.

If you want to treat them as ordinary characters you have two options:

1. Escape the metacharacter with a backslash,
2. Enclose the whole string that contains metacharacters within Q and E

Q means: “quotes all characters until E”, while E ends the quotes.

Creating an instance of the object used to make AJAX calls

Posted: 2006-07-11   |   Categories: JavaScript, Programming   |   Tags: AJAX

Nowadays, AJAX is a ubiquitous technology in the IT world. When you need to create the object used to send asynchronous requests to a server, you might face the browser-difference problem. Here is a JavaScript function you could use to overcome this problem:

  
// The following function creates an XMLHttpRequest object
function createHttpRequest() {
  if (typeof XMLHttpRequest != "undefined") //NOT IE {
    return new XMLHttpRequest();
  }
  else if (window.ActiveXObject) // IE {
    var sVersions = [ "MSXML2.XMLHttp.5.0",
    "MSXML2.XMLHttp.4.0","MSXML2.XMLHttp.3.0",
    "MSXML2.XMLHttp","Microsoft.XMLHttp"
    ];

    //try to get an instance of the newer version.
    //If it is not available go down till the oldest one
    for (var i = 0; i < sVersions.length; i++) {
      try {
        var ret = new ActiveXObject(sVersions[i]);
        return ret;
      }
      catch (oException) {
        //Do nothing. Just go on trying with the older versions
      }
    }
  }
  //if it gets here then no version is available
  alert("XMLHttpRequest object could not be created.");
}

As you can see this function creates the correct instance of the XMLHttpRequest object. If the browser is not Internet Explorer then it just instantiates the XMLHttpRequest object, otherwise it tries to create the correct ActiveX object used by IE to represent XMLHttpRequest. In this case it tries to instatiates the object from the newer version going down till the oldest one.