CODEWITHSUNDEEP
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ponjoh
ponjoh

Reputation: 927

Increase the value of a number in an element every x milliseconds

So I have this simple HTML:

<span id="badge">0</span>

I want the number 0 to increase by 1 every x milliseconds. How do I do that with Javascript (with or without jQuery)?

Thanks a bunch - I'm new to this :)

Upvotes: 3

Views: 15096

Answers (8)

Richard
Richard

Reputation: 22016

You should do this:

<script>
   var $badge = $('#badge'); // cache 
   setInterval(function () {
        var value = parseInt($badge.html());
        value++;
        $badge.html(value);
   }, 1000);

</script>

Assuming 1000 milliseconds.

Upvotes: 2

Robin Delaporte
Robin Delaporte

Reputation: 1

You could create a Jquery plugin, so you can reuse whenever you need.

$.fn.increment= function(options) {

 var $this = $(this);

 var coef = options.coef;

 var speed = options.speed;

 var value = 0;

 setInterval(function(){ 

    value = value + coef ;

    $this.html(value);

 }, speed);

};

And in your main javascript file : 

$("#badge").increment({coef: 1, speed:1000});

working demo : http://jsfiddle.net/8FMZh/102/

Upvotes: 0

jlb
jlb

Reputation: 19980

Something like this?

var millisecs = 10;
setInterval(function() {
  var $badge = $('#badge');
  $badge.text(parseInt($badge.text())++);
}, millisecs);

http://jsfiddle.net/iambriansreed/MPP8n/3/

Upvotes: 1

ShankarSangoli
ShankarSangoli

Reputation: 69905

You can use setInterval.

var $badge = $('#badge');
setInterval(function () {
     $badge.html(parseInt($badge.html()) + 1);
}, 1);​//Specify the milliseconds here, right it will update the value every 1 millisecond

Working demo - http://jsfiddle.net/8FMZh/

Upvotes: 0

Bergi
Bergi

Reputation: 664464

Every of the answers I see here has the same drawbacks:

  • performance issue because of selecting the DOM element every ms cycle. Especially when using a heavy library as jQuery.
  • setInterval() is probably the tool designed for that functionality, but not reliable. It can diverge a lot from the real time, especially when using a small interval. If you want exactly x executions per second, you may google for some timing libraries.

I would code:

var textNode = document.getElementById(badge).firstChild;
var start = Date.now();
window.setInterval(function update() {
    textNode.data = Math.round((new Date()-start)/ms);
}, ms);

If you don't want to start at 0, it will be trivial to add an offset (determined before the loop begins), eg.

var start = Date.now() - (textNode.data * ms || 0); // NaN catching, implicit number cast

Upvotes: 1

SpYk3HH
SpYk3HH

Reputation: 22570

A little more about timers:

// setting a variable for your timer will allow you the ability to "turn it on and off"
var tmrChangeI;
// setTimeout is a function to initiate a function once after given amount of milisecs
// whereas setInterval will continue a function until cancled every so many milisecs

// the following wil "turn on" your timer
tmrChangeI = setInterval(function() {
    var $badge = $('#badge');
    $badge.html($badge.html() + 1);
}, 500); // 500 will = every half of a second

// to "turn off" timer
clearInterval(tmrChangeI);

// or set a bool to test and use timeout to repeat till bool is false
var tmrBool = true;

// establish function to execute
function tmrFunc() {
    var $badge = $('#badge');
    $badge.html($badge.html() + 1);
    if (tmrBool) tmrChangeI = setTimeout(function() { tmrFunc(); }, 500); // 500 will = every half of a second
};

// execute function, begin timer
tmrChangeI = setTimeout(function() { tmrFunc(); }, 500);

// clear via bool allowing one more execution
tmrBool = false;

// clear by force possibly stoping next execution,
// tho in this manner it may be too late if timer is very short 
// and maybe overriden by bool still being true, this is not safest 
// but is example of how to use setTimeout
clearTimeout(tmrChangeI);

Upvotes: 0

Tom
Tom

Reputation: 4180

function increment() {
    document.getElementById("badge").value = Number(document.getElementById("badge").value) + 1;
    setTimeout("increment()",3000);
}
increment()

Upvotes: 1

pollirrata
pollirrata

Reputation: 5286

Check this http://www.w3schools.com/js/js_timing.asp

Upvotes: 0

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