Untitled

How to stop my javascript countdown?
var settimmer = 0;
$(function(){
        window.setInterval(function() {
            var timeCounter = $("b[id=show-time]").html();
            var updateTime = eval(timeCounter)- eval(1);
            $("b[id=show-time]").html(updateTime);
        }, 1000);

});

<b id="show-time">20</b>

$(function(){
        var timer = setInterval(function() {
            var timeCounter = parseInt($("b[id=show-time]").text());
            $("b[id=show-time]").text(--timeCounter); // remove one
            if(!timeCounter) clearInterval(timer);
        }, 1000);
});

// Activate timer
var iv = window.setInterval(...);

// Deactive timer
window.clearInterval(iv);

$(function() {
    // Read the start value once and store it in a variable
    var timeCounter = parseInt( $("b[id=show-time]").text() );

    // Active the counter
    var iv = window.setInterval(function() {
        // Decrement by one and write back into the document
        $("b[id=show-time]").text(--timeCounter);

        // Check if counter == 0 -> stop counting
        if (0 == timeCounter) {
            window.clearInterval(iv);
            // ...do whatever else needs to be done when counter == 0 ..
        }
    }, 1000);
});

var i = 0,
    pid = setInterval(function() {
        if (++i > 10)
            clearInterval(pid);
    }, 1000);

$(function() {
    var el  = document.getElementById('show-time'),
        pid = setInterval(function() {
            // (s - i) coerces s to Number
            var t = el.innerHTML - 1;
            el.innerHTML = t;
            if (t < 1)
                clearInterval(pid);
        }, 1000);
});

<script type="text/javascript">
$(function(){

var settimmer = 0,
    timeCounter = $("#show-time").html(),
    updateTime = timeCounter;

(function countDown() {
    timeCounter = $("#show-time").html();
    updateTime = parseInt(timeCounter)-1;
    $("#show-time").html(updateTime);
    if ( updateTime ) {
        setTimeout(countDown, 1000);
    }
})();

});
</script>

$(function(){
    var elem=$('strong[id="show-time"]'),settimmer=0,updateTime,t;
    t=window.setInterval(function() {
        updateTime=parseFloat(elem.html(),10)-1;
        if(updateTime==0) {
            window.clearInterval(t);
            elem.html('Done!');
        } else {
            elem.html(updateTime);
        }
    },1000);
});

<strong id="show-time">20</strong>