Clear or delete variable before declaring it again with javascript
<p>I am VERY NEW to javascript and am messing around with some math. I currently have:</p>

<pre><code>&lt;input disabled="disabled" type="text" id="backer-prediction-answer" width="100" value="" /&gt;

&lt;FORM&gt; 
    &lt;INPUT type="button" value="Apply" name="button1" onclick="apply()"&gt;
&lt;/FORM&gt;

&lt;script&gt;
var backerPrediction1 = document.getElementById("backer-prediction-1").value;
var backerPrediction2 = document.getElementById("backer-prediction-2").value;
var backerPrediction3 = document.getElementById("backer-prediction-3").value;
var backerPrediction4 = document.getElementById("backer-prediction-4").value;

function apply(){
    var backers = parseInt(backerPrediction1,10) + parseInt(backerPrediction2,10);
    document.getElementById("backer-prediction-answer").value = (backers);
}
&lt;/script&gt;
</code></pre>

<p>I would like to be able to hit apply and have it recalculate. Do I need to delete the variable before declaring it again? If so, how do I do that?</p>
