¿Es esto a lo que te refieres?
Código javascript
:
Ver original<html><head></head><body>
<script language="JavaScript">
function Suma2(isChecked, myValue){
myValue =myValue;
if (isChecked) document.sumar2.total2.value = parseFloat(myValue) + parseFloat(document.sumar2.Text1.value);
else document.sumar2.total2.value = parseFloat(myValue) - parseFloat(document.sumar2.Text1.value);
}
</script>
<body>
<form name="sumar2" method="POST">
<p><input type="text" value="0" name="Text1" /></p>
<p><input type="checkbox" value="63.50" name="Check1" onClick="Suma2(this.checked,this.value)" >$63.50</p>
<p><input type="checkbox" value="50.00" name="Check2" onClick="Suma2(this.checked,this.value)" >$50.00</p>
<p><input type="checkbox" value="1,252.00" name="Check3" onClick="Suma2(this.checked,this.value)" >$1,252.00</p>
<p><b><font color="#999999">$</font></b> <input id="pago" class="resultado" type="text" name="total2" value="0" disabled></p>
</form>
</body></html>
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