1 - Resultado do cálculo automático no edit

<form action="" method="post"> Valor: <input type="text" name="valor_unitario" id="valor_unitario" /> Taxa: <input type="text" name="qnt" id="qnt" value="0.10" readonly="readonly" /> Total: <input type="text" name="total" id="total" readonly="readonly" /> </form> <script type="text/javascript">function id(el) { return document.getElementById( el ); } function total( un, qnt ) { return parseFloat(un.replace(',', '.'), 10) - parseFloat(qnt.replace(',', '.'), 10); } window.onload = function() { id('valor_unitario').addEventListener('keyup', function() { var result = total( this.value , id('qnt').value ); id('total').value = String(result.toFixed(2)).formatMoney(); }); id('qnt').addEventListener('keyup', function(){ var result = total( id('valor_unitario').value , this.value ); id('total').value = String(result.toFixed(2)).formatMoney(); }); } String.prototype.formatMoney = function() { var v = this; if(v.indexOf('.') === -1) { v = v.replace(/([\d]+)/, "$1,00"); } v = v.replace(/([\d]+)\.([\d]{1})$/, "$1,$20"); v = v.replace(/([\d]+)\.([\d]{2})$/, "$1,$2"); v = v.replace(/([\d]+)([\d]{3}),([\d]{2})$/, "$1.$2,$3"); return v; }; </script>

Valor:
Taxa:
Total: