Date.prototype.adjust

Friday, February 23, 2007

I thought someone might find this useful: the Date.prorotype.adjust() function for adjusting a javascript date. It allows you to create a date object and then increment or decrement the years, months, days, hours, minutes or seconds easily: d.adjust(years, months, days, hours, minutes, seconds). [Update] OIK! Bone-headed bug fixed. Corrected code below.

Usage:

var d = new Date();
d.adjust(years, months, days, hours, minutes, seconds); 

• All the arguments are required, use 0 for no adjustments
• Use negative numbers to go back in time
• Year roll over is handled, for example if you add 15 months.

For example, this code will adjust a date 3 months and 5 days into the future:

var d = new Date();
d.adjust(0, 3, 5, 0, 0, 0); 

And here's the simple but useful code:

Date.prototype.adjust = function(yr,mn,dy,hr,mi,se) {
var m,t;
this.setYear(this.getFullYear() + yr);
m = this.getMonth() + mn;
if(m != 0) this.setYear(this.getFullYear() + Math.floor(m/12));
if(m < 0) {
this.setMonth(12 + (m%12));
} else if(m > 0) {
this.setMonth(m%12);
}
t = this.getTime();
t += (dy * 86400000);
t += (hr * 3600000);
t += (mi * 60000);
t += (se * 1000);
this.setTime(t);
}

Random outings from a chaotic mind