JavaScript - Date, Array and Math Object

Date Object

The Date object is used to work with dates and times. Date objects are created with the Date() constructor. There are four ways of instantiating a date:

new Date() // current date and time

new Date(milliseconds) //milliseconds since 1970/01/01 new Date(dateString)

new Date(year, month, day, hours, minutes, seconds, milliseconds)

Example:

today = new Date()

d1 = new Date("October 13, 1975 11:13:00")

d2 = new Date(79,5,24)

d3 = new Date(79,5,24,11,33,0)

Compare Two Dates

The Date object is also used to compare two dates. The following example compares today's date with the 15th August 2012:

var myDate=new Date(); myDate.setFullYear(2012,7,15); var today = new Date();

if (myDate>today)

{

alert("Today is before 15th August 2012");

}

else

{

alert("Today is after 15th August 2012");

}

Array Object

An array is a special variable, which can hold more than one value, at a time. An array can be defined in three ways. The following code creates an Array object called myCars:

1.    var myCars=new Array(); // regular array (add an optional integer myCars[0]="Saab"; // argument to control array's size) myCars[1]="Volvo";

myCars[2]="BMW";

2.     var myCars=new Array("Saab","Volvo","BMW"); // condensed array

3.     var myCars=["Saab","Volvo","BMW"]; // literal array

Math Object

The Math object allows you to perform mathematical tasks. The Math object includes several mathematical constants and methods.