Change value of a variable inside a timer event Javascript

Question

I am increasing value of a variable inside a timer.It is also inside a button onClick event.

setInterval(function () {
    document.getElementById('z_in').addEventListener('click', function () {
        zoom_level = 1;
    }, false);
    document.getElementById('z_out').addEventListener('click', function () {
        zoom_level = 3;
    }, false);
    document.getElementById('rotate').addEventListener('click', function () {
        angle = angle + 10;

    }, false);
    Find(db, minLon, maxLon, minLat, maxLat, zoom_level, angle, stage, layer, i);
    i++;
    //angle = 0;
    console.log();
}, 1000);

Here angle increases too much not ten by ten in every loop.What is the reason of this problem?

You add an additional eventlistener each second. Thus angle increases by ten for every eventlistener added. — Moritz Roessler
– Moritz Roessler, Commented Sep 19, 2013 at 8:53
An offtopic question: which facts had spoken for it to pass complete javascript functions as parameters? In my eyes it is bad practise and makes it harder to read forign code. — Reporter
– Reporter, Commented Sep 19, 2013 at 8:53
jsfiddle.net/PPzQv you can see angle values in console.It does not increases ten by ten. — mekafe
– mekafe, Commented Sep 19, 2013 at 8:55

Anton · Accepted Answer · 2013-09-19 10:37:01Z

2

If you need listeners only when timer is active, you can use something like this:

var timer, i = 0, zoom_level = 1, angle = 0;
var z_in_el = document.getElementById('z_in');
var z_out_el = document.getElementById('z_out');
var rotate_el = document.getElementById('rotate');

function zoomIn(){
    zoom_level = 1;
}
function zoomOut(){
    zoom_level = 3;
}
function rotate(){
    angle += 10;
}

function startTimer(){
    addListeners();
    timer = window.setInterval(function(){
        i++;
        Find(db, minLon, maxLon, minLat, maxLat, zoom_level, angle, stage, layer, i);
        console.log(i, zoom_level, angle);
    }, 1000); 
}

function stopTimer(){
    removeListeners();
    window.clearInterval(timer);
}

function addListeners(){
    z_in_el.addEventListener("click", zoomIn, false);
    z_out_el.addEventListener("click", zoomOut, false);
    rotate_el.addEventListener("click", rotate, false);
}

function removeListeners(){
    z_in_el.removeEventListener("click", zoomIn, false);
    z_out_el.removeEventListener("click", zoomOut, false);
    rotate_el.removeEventListener("click", rotate, false);
}

Use startTimer() to set interval or stopTimer() to remove it.

edited Sep 19, 2013 at 10:37

answered Sep 19, 2013 at 8:51

Anton

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2 Comments

Anton Over a year ago

Fixed answer. Is it what you need?

mekafe Over a year ago

Yep.Thank you so much Anton.That would be so very useful for me.

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