How do I reset the setInterval timer?

Question

How do I reset a setInterval timer back to 0?

var myTimer = setInterval(function() {
  console.log('idle');
}, 4000);

I tried clearInterval(myTimer) but that completely stops the interval. I want it to restart from 0.

Answer 1

If by "restart", you mean to start a new 4 second interval at this moment, then you must stop and restart the timer.

function myFn() {console.log('idle');}  var myTimer = setInterval(myFn, 4000);  // Then, later at some future time,  // to restart a new 4 second interval starting at this exact moment in time clearInterval(myTimer); myTimer = setInterval(myFn, 4000); 

---

You could also use a little timer object that offers a reset feature:

function Timer(fn, t) {     var timerObj = setInterval(fn, t);      this.stop = function() {         if (timerObj) {             clearInterval(timerObj);             timerObj = null;         }         return this;     }      // start timer using current settings (if it's not already running)     this.start = function() {         if (!timerObj) {             this.stop();             timerObj = setInterval(fn, t);         }         return this;     }      // start with new or original interval, stop current interval     this.reset = function(newT = t) {         t = newT;         return this.stop().start();     } } 

Usage:

var timer = new Timer(function() {     // your function here }, 5000);   // switch interval to 10 seconds timer.reset(10000);  // stop the timer timer.stop();  // start the timer timer.start(); 

Working demo: https://jsfiddle.net/jfriend00/t17vz506/

Answer 2

Once you clear the interval using clearInterval you could setInterval once again. And to avoid repeating the callback externalize it as a separate function:

var ticker = function() {
    console.log('idle');
};

then:

var myTimer = window.setInterval(ticker, 4000);

then when you decide to restart:

window.clearInterval(myTimer);
myTimer = window.setInterval(ticker, 4000);