JAVASCRIPT - Calculadora con botón de encendido

Calculadora con botón de encendido

Compatibilidad: Ms Internet Explorer, Netscape
Una normal calculadora en javascript que se caracteriza por la presencia de un botón de apagado.

[ Muestra el ejemplo práctico ]

el código para insertar en tu página

<TITLE>Ejemplos Javascript: ejemplo práctico </TITLE>

/*******************************************************

**       S.Christopher Brown's (Spikeman)'s            **

**             java script Calculator                  **

**   http://www.geocities.com/BourbonStreet/3843       **

**  You can freely use  this script, if this credit is **

** given in the source. So that mean don't mess around **

** with my ( Spikeman ) Script or Script's k ?         **

**                  Thank you                          **

*******************************************************/

// This JavaScript code Originally by S.Chris Brown  (Spikeman) 1996 - 1997 ( http://www.geocities.com/BourbonStreet/3843 )

<!-- Hide the script from browsers which do not support it.

// Global Variables

var acc = 0;            // accumulator for calculations

var oper = " ";         // the previous operation

var startnum = true;    // is this a new number

var decpoint = false;   // is there a decimal point

var errorstate = false; // an error has occured so lock keys until "AC" is pressed

// Global "Constants" (...)

MAXLEN = 14;

// IsNumeric - returns true if a string is a valid numeric literal

function IsNumeric(num) {

var idx = 0;

var ch = "";

var foundpoint = false;

for (idx = 0; idx < num.length; idx++) {

ch = num.substring(idx, idx +1 );

if ((ch < "0") || (ch > "9")) {

if ((ch == ".") && (!foundpoint)) {

foundpoint = true;

continue;

} else {

if ((ch == "-") && (idx == 0)) {

continue;

}

return false;

}

} // for idx

return true;

}

// ContainsChar - check if a string contains a certain char

function ContainsChar(str, ch) {

var idx;

for (idx = 0; idx < str.length; idx++) {

if (str.substring(idx, idx + 1) == ch) {

return true;

}

}   // for idx

return false;

}

// ContainsDecimalPoint - check if a number string contains a decimal point

function ContainsDecimalPoint(num) {

return ContainsChar(num, ".");

}

// DisplayChanged - the display was explicitly changed, so check if it is valid

function DisplayChanged(form, display) {

if (!errorstate) {

if (IsNumeric(display.value)) {

display.defaultValue = display.value;

startnum = false;

decpoint = ContainsDecimalPoint(display.value);

} else {

alert("You must enter a numeric value here.");

display.value = display.defaultValue;

}

} else {   // errorstate

alert('An error has occured. Press the "AC" button.');

}

// NumPressed - a digit button was pressed, add it to the current display

function NumPressed(form, digit) {

if (!errorstate) {

if ((digit !=0) || (form.display.value != "0")) {

if (startnum) {   // need to put a new number on the display (e.g. after "=")

form.display.value = eval(digit);

} else {

if (form.display.value.length < MAXLEN) {

form.display.value = form.display.value + digit;

}   // enough room to put new digit

}   // add the digit

startnum = false;

form.display.defaultValue = form.display.value;

}   // not trying to add leading zeros

} else {   //errorstate

alert('An error has occured. Please press the "AC" button');

}

// ChangeSign - "+/-" button was pressed, change sign of current display

function ChangeSign(form) {

if (!errorstate) {

if (form.display.value != "0") {

if (eval(form.display.value) < 0) {   // negative no problem

form.display.value = 0 - eval(form.display.value);

} else {   // positive, make sure it's not too long

if (form.display.value.length < MAXLEN)

form.display.value = 0 - eval(form.display.value);

}   // positive

form.display.defaultValue = form.display.value;

startnum = false;

}   // not 0, can be negated

} else {   // errorstate

alert('An error has occured. Please press the "AC" button');

}

// PointPressed - the decimal dot was pressed, add it to number and start putting disits after it

function PointPressed(form) {

if (!errorstate) {

if ((!decpoint) && (form.display.value.length < MAXLEN - 1)) {

if (startnum) {

form.display.value = "0";

}    // start a new number

form.display.value = form.display.value + ".";

form.display.defaultValue = form.display.value;

decpoint = true;

startnum = false;

}   // decimal point not already present

} else {   // errorstate

alert('An error has occured. Please press the "AC" button');

}

// ClearAll - "AC" button was pressed, restart the calculator

function ClearAll(display) {

display.value = "0";

display.defaultValue = "0";

decpoint = false;

acc = 0;

oper = " ";

startnum = true;

errorstate = false;

}

// ClearNum - "C" button was pressed, clear only current number on display

function ClearNum(display) {

if (!errorstate) {

display.value = "0";

display.defaultValue = "0";

decpoint = false;

startnum = true;

} else {   // errorstate

alert('An error has occured. Please press the "AC" button');

}

// RemoveZeros - remove leading zeros after a decimal point from a number string

function RemoveZeros(num) {

var idx;

if (ContainsChar(num, ".")) {

idx = num.length - 1;

ch = num.substring(idx, idx + 1);

while((idx > 0) && (ch == "0")) {

idx--;

ch = num.substring(idx, idx + 1);

}

num = num.substring(0, idx + 1);

// get rid of a trailing decimal point, if it remained hanging after the torture ...

if (num.substring(num.length - 1, num.length) == ".") {

num = num.substring(0, num.length - 1)

}

}   // num contains a decimal point

return num;

}

// CalcDisplay - calculate the new display using the accumulator and the previous operator

function CalcDisplay(display) {

if (oper == "+") {

display.value = acc + eval(display.value);

} else if (oper == "-") {

display.value = acc - eval(display.value);

} else if (oper == "*") {

display.value = acc * eval(display.value);

} else if (oper == "/") {

if (display.value == "0") {

display.value = "ERROR !"

errorstate = true;

} else {

display.value = acc / eval(display.value);

}

if (!errorstate) {

if ((eval(display.value) >= eval("1e" + MAXLEN)) || (eval(display.value) <= eval("-1e" + (MAXLEN - 1)))) {

display.value = "ERROR !";

errorstate = true;

} else {

if (!ContainsChar(display.value, "e")) {   // not exponential format

if (display.value.length > MAXLEN) {

// number is in permited range, so extra digits are after decimal point

// truncate extra digits

display.value = display.value.substring(0, MAXLEN);

// get rid of a hanging decimal point

if (display.value.substring(MAXLEN - 1, MAXLEN) == ".") {

display.value = display.value.substring(0, MAXLEN - 1);

} else {

// get rid of trailing zeros

display.value = RemoveZeros(display.value);

}

}   // string too long

} else {   // exponential format

// Numbers smaller than 0.00001 are represented in exponential notation by the browser.

// A piece of code to translate them to fix notation should be put here.

// This is getting *much* too boring for me, so I leave it as is.

// If anyone has the will power to write it, I'll be glad to include it ...

}   // exponential format

}   // not too high or low

}   // no error yet (division by zero)

display.defaultValue = display.value;

}

// OperPressed - calculate the new display and move it to the accumulator

function OperPressed(form, newoper) {

if (!errorstate) {

CalcDisplay(form.display);

oper = newoper;

acc = eval(form.display.value);

startnum = true;

decpoint = false;

} else {   // errorstate

alert('An error has occured. Please press the "AC" button');

}

// CalcResult - the "=" button was pressed, put result on display

function CalcResult(form) {

if (!errorstate) {

CalcDisplay(form.display);

oper = " ";

acc = 0;

startnum = true;

decpoint = false;

} else {   // errorstate

alert('An error has occured. Please press the "AC" button');

}

// End of hiding script from browsers which do not support it. -->

</SCRIPT>

</HEAD>

<FORM>

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<HR><h4> ~`~ Scripts By Spikeman ~`~</h4><HR>

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</TABLE>

</FORM>

</body>
</html>

[Baja en un único archivo .zip, las imágenes y demás archivos necesarios
para el funcionamiento de los script de esta sección]