javascript - clearTimeout on dynamically updating timer -

i've got timer i'm updating dynamically.

------------------update -------------------------- when first posted question, didn't think mattered timer being called within backbone view, believe result of that, can't use global variable (or @ least global variable isn't working). i'll calling multiple timers, setting 1 global variable , deleting won't work. need able clear single timer without clearing others.

what start timer,

  function countdown(end_time, divid){     var tdiv = document.getelementbyid(divid),         to;     this.rewritecounter = function(){         if (end_time >= myapp.start_time)       {           tdiv.innerhtml =  math.round(end_time - myapp.start_time);       }       else {         alert('times up');       }     };     this.rewritecounter();     = setinterval(this.rewritecounter,1000); } 

in app, initiate timer in backbone view

 myapp.views.timer = backbone.view.extend({  el: 'div#timer',   initialize: function(){      timer = this.model;      this.render();  },  events: {     "clicked div#add_time": "update_timer"  }   render: function(){     $(this.el).append(handlebarstemplates['timer'](timer);     this.start_timer();  },  start_timer: function(){     delete main_timer; // doesn't work :(     cleartimtout(main_timer); //this doesn't work either :(      var main_timer = settimeout(new countdown(timed.length, 'main_timer'),timed.length*1000);  },   update_timer: function(){    timed.length=timed.length+30   this.start_timer();  } }); 

so i'm trying update timer, kill old timer, , restart new values. have different timers, calling timed.length within countdown function won't work.

var main_timer = settimeout(new countdown(timed.length, 'main_timer'),timed_length*1000); 

this statement creates local variable main_timer. instead have create global variable , use clear time out shown below

cleartimtout(main_timer); main_timer = settimeout(new countdown(timed.length, 'main_timer'),timed_length*1000); 

edit:

use function settimeout handler shown below

cleartimeout(main_timer);  main_timer = settimeout(function(){     new countdown(timed.length, 'main_timer'); },timed_length*1000); 

note: hope timed.length , timed_length correct.

edit:

modify countdown given below.

function countdown(end_time, divid){     var tdiv = document.getelementbyid(divid),         to;     this.rewritecounter = function(){         if (end_time >= myapp.start_time)       {           tdiv.innerhtml =  math.round(end_time - myapp.start_time);       }       else {         alert('times up');       }     };      this.clearrewritecounter = function(){       clearinterval(to);     }      this.rewritecounter();     = setinterval(this.rewritecounter,1000);      return this; } 

and in myapp.views.timer

myapp.views.timer = backbone.view.extend({  el: 'div#timer',   initialize: function(){      timer = this.model;      this.render();  },  events: {     "clicked div#add_time": "update_timer"  }   render: function(){     $(this.el).append(handlebarstemplates['timer'](timer);     this.start_timer();  },  start_timer: function(){     cleartimeout(this.main_timer);      this.main_timer = settimeout(function(){         if(this.countdowninstance){             this.countdowninstance.clearrewritecounter();         }         this.countdowninstance = new countdown(timed.length, 'main_timer');     },timed_length*1000);  },   update_timer: function(){    timed.length=timed.length+30   this.start_timer();  } });