Stop countdown when it reaches to "0"
<p>I want to stop this counter when it reaches to 0, can anyone help me?</p>

<pre><code>function countdown() {
    var i = document.getElementById('counter');
    if (parseInt(i.innerHTML)&lt;=0) {
    }
    i.innerHTML = parseInt(i.innerHTML)-1;
}
setInterval(function(){ countdown(); },1000);
</code></pre>
