datetime - Javascript Time - Run a Function every Half Hour (Solved) -

i made function 2 things: returns amount of time until next thirty minute mark, , calls halfhour function when timer reaches zero. if time 12:06:27, output 24:33 (mm:ss)

function checktime() {   var time = new date();   var mins = time.getminutes();   mins = (60-mins) % 30;   var secs = time.getseconds();   if (secs != 60){   secs = (60-secs) % 60;   } else {   secs = 00;   }   time = [number(mins),number(secs)];   if (mins == 0 && secs == 0){     halfhour();   }   return time; } 

this works, there strange glitch. when minute rolls over, shows... 24:02 24:01 23:00 23:59 23:58

it calls halfhour(); 1 minute soon, @ false 0:00 mark in last sequence: 1:02 1:01 0:00 0:59

how can correct this?

edit: commenters dbrin , njzk2 have solution. it's subtracting minutes , seconds 59 instead of 60. below modified working code. sorry it's messy.

function checktime() {   var time = new date();   var mins = time.getminutes();   mins = (59-mins) % 30;   var secs = time.getseconds();   if (secs != 60){   secs = (59-secs) % 60;   } else {   secs = 00;   }   time = [number(mins),number(secs)];   if (mins == 0 && secs == 0){     halfhour();   }   return time; } 

thank sharing!

why reinvent wheel when javascript has built in setinterval(code, delay); acheive this.

setinterval(function() {     alert("i fire after every 2 seconds") }, 2000);