Calculate Age from given Birthdate

As there was a requirement in my project to calculate age(Age in Year,Age in Month,Age in days) of an entity from his/her birthdate to the present date.

I have created one function in javascript which will calculate age(Age in Year,Age in Month,Age in days) from given birthdate.

The function is as given below.

1function CalculateAgeFromBirthdate(birthdate)
2{
3
4 var birthdate;
5 birthdate = new Date(birthdate);
6
7 var bYear = birthdate.getFullYear();//Year of birth
8 var bMonth = birthdate.getMonth() + 1; //Month of Birth
9 var bDay = birthdate.getDate(); //Day of Birth
10
11 var date = new Date(); // get current date
12 var cYear = date.getFullYear(); //Get current year
13 var cMonth = date.getMonth() + 1;//Get current month
14 var cDay = date.getDate();//Get Current Date
15
16 var g31Day=new Array(1,3,5,7,8,10,12);//Array of the months of 31 days
17 var g30Day=new Array(2,4,6,9,11); //Array of the months of 30 days
18 var gMonth=12;
19 var gDay;
20
21 var getCurentMont=cMonth//get current month
22 var getCurrentYear=cYear//get current year
23
24 for(var i=0;i < g31Day.length;i++)
25{
26
27
28 if (g31Day[i]== getCurentMont)
29{
30 gDay=31;
31 break;
32 }
33
34 }
35 for(var i=0;i < g30Day.length; i++)
36 {
37
38 if(g30Day[i] == getCurentMont)
39{
40 if(getCuurentMont=2)
41 {
42 //For leap year
43 if(getCurrentYear % 4 == 0 (getCurrentYear % 100 != 0 && getCurrentYear % 4 == 0))
44{
45 gDay=29;
46 break;
47 }
48 else
49{
50 gDay=28;
51 break;
52 }
53
54 }
55 else
56{
57 gDay=30;
58 break;
59 }
60 }
61 }
62
63 var years;
64 var Day;
65 var Month;
66
67 years = (cYear) -parseInt(bYear);
68
69 Day = parseInt(cDay)-parseInt(bDay);
70
71 Month = (cMonth)-parseInt(bMonth);
72
73
74 if( Month < 0)
75
76{
77
78 gMonth=parseInt(gMonth)+ parseInt(Month) ;
79
80 Month=gMonth;
81 years--;
82 flag=true;
83
84 }
85 if( Day < 0)
86
87{
88
89 gDay=parseInt(gDay)+ parseInt(Day) ;
90
91 Day=gDay;
92
93 }
94
95 alert("I am of "+years+" years, "+Month+" month and "+Day +" days");
96
97 }

By passing Birthdate as Parameter it will calculate the age.