Calculadora en JavaScript

Ingeniosa solución para crear una calculadora con java scrpt realizado por mundojavascript.

Código

<FORM name="Keypad" action=""> <B> <TABLE border=2 width=50 height=60 cellpadding=1 cellspacing=5 > <TR> <TD colspan=3 align=middle> <input name="ReadOut" type="Text" size=24 value="0" width=100% > </TD> <TD> </TD> <TD> <input name="btnClear" type="Button" value=" C " onclick="Clear()" > </TD> <TD><input name="btnClearEntry" type="Button" value=" CE " onclick="ClearEntry()" > </TD> </TR> <TR> <TD> <input name="btnSeven" type="Button" value=" 7 " onclick="NumPressed(7)" > </TD> <TD> <input name="btnEight" type="Button" value=" 8 " onclick="NumPressed(8)" > </TD> <TD> <input name="btnNine" type="Button" value=" 9 " onclick="NumPressed(9)" > </TD> <TD> </TD> <TD> <input name="btnNeg" type="Button" value=" +/- " onclick="Neg()" > </TD> <TD> <input name="btnPercent" type="Button" value=" % " onclick="Percent()" > </TD> </TR> <TR> <TD> <input name="btnFour" type="Button" value=" 4 " onclick="NumPressed(4)" > </TD> <TD> <input name="btnFive" type="Button" value=" 5 " onclick="NumPressed(5)" > </TD> <TD> <input name="btnSix" type="Button" value=" 6 " onclick="NumPressed(6)" > </TD> <TD> </TD> <TD align=middle><input name="btnPlus" type="Button" value=" + " onclick="Operation('+')" > </TD> <TD align=middle><input name="btnMinus" type="Button" value=" - " onclick="Operation('-')" > </TD> </TR> <TR> <TD> <input name="btnOne" type="Button" value=" 1 " onclick="NumPressed(1)" > </TD> <TD> <input name="btnTwo" type="Button" value=" 2 " onclick="NumPressed(2)" > </TD> <TD> <input name="btnThree" type="Button" value=" 3 " onclick="NumPressed(3)" > </TD> <TD> </TD> <TD align=middle><input name="btnMultiply" type="Button" value=" * " onclick="Operation('*')" > </TD> <TD align=middle><input name="btnDivide" type="Button" value=" / " onclick="Operation('/')" > </TD> </TR> <TR> <TD> <input name="btnZero" type="Button" value=" 0 " onclick="NumPressed(0)" > </TD> <TD> <input name="btnDecimal" type="Button" value=" . " onclick="Decimal()" > </TD> <TD colspan=3> </TD> <TD> <input name="btnEquals" type="Button" value=" = " onclick="Operation('=')" > </TD> </TR> </TABLE> </B> </FORM> <SCRIPT LANGUAGE="JavaScript"> <!-- Este script y muchos mas estan disponibles en --> <!-- Galeria de javaScript http://www16.brinkster.com/galeriajs --> <!-- Begin var FKeyPad = document.Keypad; var Accum = 0; var FlagNewNum = false; var PendingOp = ""; function NumPressed (Num) { if (FlagNewNum) { FKeyPad.ReadOut.value = Num; FlagNewNum = false; } else { if (FKeyPad.ReadOut.value == "0") FKeyPad.ReadOut.value = Num; else FKeyPad.ReadOut.value += Num; } } function Operation (Op) { var Readout = FKeyPad.ReadOut.value; if (FlagNewNum && PendingOp != "="); else { FlagNewNum = true; if ( '+' == PendingOp ) Accum += parseFloat(Readout); else if ( '-' == PendingOp ) Accum -= parseFloat(Readout); else if ( '/' == PendingOp ) Accum /= parseFloat(Readout); else if ( '*' == PendingOp ) Accum *= parseFloat(Readout); else Accum = parseFloat(Readout); FKeyPad.ReadOut.value = Accum; PendingOp = Op; } } function Decimal () { var curReadOut = FKeyPad.ReadOut.value; if (FlagNewNum) { curReadOut = "0."; FlagNewNum = false; } else { if (curReadOut.indexOf(".") == -1) curReadOut += "."; } FKeyPad.ReadOut.value = curReadOut; } function ClearEntry () { FKeyPad.ReadOut.value = "0"; FlagNewNum = true; } function Clear () { Accum = 0; PendingOp = ""; ClearEntry(); } function Neg () { FKeyPad.ReadOut.value = parseFloat(FKeyPad.ReadOut.value) * -1; } function Percent () { FKeyPad.ReadOut.value = (parseFloat(FKeyPad.ReadOut.value) / 100) * parseFloat(Accum); } // End --> </SCRIPT> <br><br> <center><small><small>Este script y muchos mas est&aacute;n disponibles en<br> <a href="http://www.precios10.com/mundojavascript">Mundo Javascript</small></small></a></center>

Sólo copia y pega el código en un bloc de notas y guárdalo como Calculadora.html o cualquier nombre pero con extensión html.
fuente: http://www.precios10.com/mundojavascript