Bob Leurck @Google

2009-02-24T18:15:00.000-08:00

A distributed web architecture allows for separation of site support services to the maximum extent possible. This is achieved by adopting the web service interface paradigm at the business facade. The UI elements , served by a web platform can obtain their business objects from one or many network services, not a central EJB or App Server technology. In this fashion those business objects and transactions that require pools of servers to meet their performance objectives can be scaled quickly and easily at low cost with simple hardware and not scale based on increasing cpus on a single server . This approach can be applied across web technologies and tools.

August 07 json.js breaks for in loops

2007-09-14T13:34:00.000-07:00

I like this new json.js implementation. However, Douglas Crockford extends Object , and Array so all my for in loops are broken.

A simple solution for Array is :

var aList = new Array();
aList.push("A");
aList.push("B");

for (var propertyName in aList)
{
// must know type of aList
if (Array.prototype[propertyName] === undefined)// skip any extensions
{
alert(aList[propertyName]);
}
}

Thanks to this post for this technique.

FYI Douglas Crockford has a reccomendation for this .
Please see the discussion on DontEnum .

Scope and Bind in Javascript and Prototype

2007-09-13T14:21:00.000-07:00

Just read this and wanted to remember it . A great article on Prototype bind and variable scope in Javascript. Nice graphics too !

2007-04-26T11:28:00.000-07:00

A great intro to javascript objects .
http://www.crockford.com/javascript/private.html

And a nice discussion is here.
http://www.sitepoint.com/article/javascript-objects

With my slight modifications below:
You can cut and paste this into a js file and call from a page

/*
script src="yourSavedFileName.js"
*/

Object.prototype.addProperty = function (sType, sName, vValue) {

if (typeof vValue != sType) {
alert("Property " + sName + " must be of type " + sType + ".");
return;
}

this[sName] = vValue;

var sFuncName = sName.charAt(0).toUpperCase() + sName.substring(1, sName.length);

this["get" + sFuncName] = function () { return this[sName] };
this["set" + sFuncName] = function (vNewValue) {

if (typeof vNewValue != sType) {
alert("Property " + sName + " must be of type " + sType + ".");
return;
}

var vOldValue = this["get" + sFuncName]();
var oEvent = {
propertyName: sName,
propertyOldValue: vOldValue,
propertyNewValue: vNewValue,
returnValue: true
};
this.onpropertychange(oEvent);
if (oEvent.returnValue) {
this[sName] = oEvent.propertyNewValue;
}

};
}

/*
the typeof operator returns one of the following values:

* "undefined" the value doesn’t exist.
* "string"
* "number"
* "function"
* "object"
* "boolean"
*/

//sample implementation

var ClassB= function(){
var iamPrivate = 5;
this.publicX = 10;
this.addProperty("string", "message", "Hello world");
this.addProperty("string", "name", "Nicholas C. Zakas");
this.addProperty("number", "age", 25);

this.setPrivate = function(val) {
iamPrivate = val;
};

this.getPrivate = function() {
return iamPrivate ;
};

this.onpropertychange = function(oEvent) {
if (oEvent.propertyName == "name") {
oEvent.returnValue = false; //don’t allow name to be changed
}
};
};

var Test = new ClassB();
alert(Test.getMessage()); //outputs "Hello world"
Test.setMessage("Goodbye world");
alert(Test.getMessage()); //outputs "Goodbye world"
alert(Test.getName()); //outputs "Nicholas C. Zakas"
Test.setName("Michael A. Smith");
alert(Test.getName()); //outputs "Nicholas C. Zakas"

// now override onpropertychange

Test.onpropertychange = function(oEvent) {
if (oEvent.propertyName == "age") {
oEvent.returnValue = false; //don’t allow name to be changed
}
}
Test.setName("Michael A. Override");
alert(Test.getName()); //outputs "Michael A. Override"
alert(Test.getAge()); //outputs 25
Test.setAge("45"); //generates error message
alert(Test.getAge()); //outputs 25
Test.setAge(35); //sets value
alert(Test.getAge()); //outputs 25 since onpropertychange was overridden
alert(Test.publicX);
Test.publicX = 15;
alert(Test.publicX); // no private variables
alert(Test.getPrivate()); // returns 5
alert(Test.iamPrivate); // not exist - undefined

2007-03-14T09:40:00.000-07:00

Check out www.meebo.com. It is an html/javascript/browser interface to instant messaging systems. They also have a widget "meebome" which allows visitors to a web page to chat with the person on the other end of the meebome widget. The front door for the networked society ! (Until spammers and direct marketers make you "close" your front door.)

2007-03-06T04:48:00.001-08:00

Welcome