Archive for the 'JavaScript' Category

Object Or Array Check in JavaScirpt

Test whether an object is an object or an array


if(Object.prototype.toString.apply(arr) === '[object Array]') alert("Array")

Original Article

Change shell

Change shell command


chsh

Finding the Factorial using Recursion

Finding the Factorial using Recursion in javascript.


function factorial(x) {
	if(x <= 1) return 1;
	return x*factorial(x-1);
}
factorial(5);

A Simple Logging Function for JavaScript

Prints all the arguments of the function. This function uses console.log if firebug is available – else, uses alert.


function p() {
                for(var i=0; i<<arguments.length; i++) {
			if(window.console) console.log(arguments[i]);
			else alert(arguments[i]);
		}
}

Chainable interface in JavaScript

Creating Chainable interfaces in javascript…


(function() {
	function _init() {
		return this;
	}
	
	_init.prototype = {
		"myFunction": function() {
			return this;
		}
		
		// Put all the functions here - make sure all 'return this;'
	}
	
	chainer = function() {
		return new _init();
	}
})();

Roll out your own JavaScript Interfaces

[tags][/tags]

Execute JavaScript files using Rhino

The command to execute a javascript file using rhino.


java -jar /path/to/custom_rhino.jar JS_File.js

Get Custom Rhino(From Dojo Library)

Install Rhino

Installing Rhino(Javascript interpreter created in java) on Fedora 7


sudo yum install rhino-manual rhino-demo rhino

Scope and Binding in JavaScript

Function x executions in the scope of object y.


var Car = function() { this.name = 'car'; }
var Truck = function() { this.name = 'truck'; }

var func = function() { alert(this.name); }

var c = new Car();
var t = new Truck();

func.apply(c);
func.apply(t);

Original Article
[tags]javascript,apply,call,binding[/tags]

Find Element’s Position using JavaScript

Find the position of an element using javascript


function findPos(obj) {
	var curleft = curtop = 0;
	if (obj.offsetParent) {
		curleft = obj.offsetLeft
		curtop = obj.offsetTop
		while (obj = obj.offsetParent) {
			curleft += obj.offsetLeft
			curtop += obj.offsetTop
		}
	}
	return [curleft,curtop];
}

Original Article

Find the Fourth Sunday

Javascript code for finding the fourth sunday in any given month.


function findFourthSunday(year,month) {
	var fourth_sunday = 0;
	var sunday_count = 0;
	//There is a really cool solution for this
	//forth_sunday = 29 - first_day_of_month
	//But the problem is if the first of month is a sunday(first_day_of_month == 0), then there will be a bug. Found the bug in April 2007 ;-)

	for(var i=1;i<31;i++) {
		var a_day = new Date(year,month,i);
		if(a_day.getDay() == 0) sunday_count++;//'0' means sunday - 1 for monday, etc.
		
		if(sunday_count == 4) {
			fourth_sunday = i;
			break;
		}
	}
	return fourth_sunday;
}
function init() {
	var month_names = new Array("January","February","March","April","May","June","July","Augest","September","October","November","December");
	var first_day = ""
	var today = new Date();
	var year = today.getYear();
	year = (year > 2000) ? year : year + 1900;
	var month = today.getMonth();
	
	var fourth_sunday = findFourthSunday(year,month);
	if(today.getDate() > fourth_sunday) {
		month ++;
		fourth_sunday = findFourthSunday(year,month);
	} else if(today.getDate() == fourth_sunday) {
		fourth_sunday = "Today - " + fourth_sunday;
	}
	var date = fourth_sunday + " " + month_names[month] + ", " + year;
	alert(date);
}
window.onload=init;

[tags]javascript,fourth,sunday,calender,month,date,day,code[/tags]