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DerekRies/gist:6290137

Created August 21, 2013 03:45
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gistfile1.txt
<!doctype html>
<html>
<head>
<meta charset="UTF-8">
<title>Untitled Document</title>
<script type="text/javascript">
<!--------------------------------------------------------------------
Memory = "0"; // initialise memory variable
Current = "0"; // and value of Display ("current" value)
Operation = 0; // Records code for eg * / etc.
MAXLENGTH = 30; // maximum number of digits before decimal!
function AddDigit(dig) //ADD A DIGIT TO DISPLAY (keep as 'Current')
{ if (Current.indexOf("!") == -1) //if not already an error
{ if ( (eval(Current) == 0)
&& (Current.indexOf(".") == -1)
) { Current = dig;
} else
{ Current = Current + dig;
};
Current = Current.toLowerCase(); //FORCE LOWER CASE
} else
{ Current = "Hint! Press 'AC'"; //Help out, if error present.
};
if (Current.indexOf("e0") != -1)
{ var epos = Current.indexOf("e");
Current = Current.substring(0,epos+1) + Current.substring(epos+2);
};
if (Current.length > MAXLENGTH)
{ Current = "Aargh! Too long"; //don't allow over MAXLENGTH digits before "." ???
};
document.Calculator.Display.value = Current;
}
function Dot() //PUT IN "." if appropriate.
{
if ( Current.length == 0) //no leading ".", use "0."
{ Current = "0.";
} else
{ if ( ( Current.indexOf(".") == -1)
&&( Current.indexOf("e") == -1)
)
{ Current = Current + ".";
}; };
document.Calculator.Display.value = Current;
}
function DoExponent()
{
if ( Current.indexOf("e") == -1 )
{ Current = Current + "e0";
document.Calculator.Display.value = Current;
};
}
function PlusMinus()
{
if (Current.indexOf("e") != -1)
{ var epos = Current.indexOf("e-");
if (epos != -1)
{ Current = Current.substring(0,1+epos) + Current.substring(2+epos); //clip out -ve exponent
} else
{ epos = Current.indexOf("e");
Current = Current.substring(0,1+epos) + "-" + Current.substring(1+epos); //insert -ve exponent
};
} else
{ if ( Current.indexOf("-") == 0 )
{ Current = Current.substring(1);
} else
{ Current = "-" + Current;
};
if ( (eval(Current) == 0)
&& (Current.indexOf(".") == -1 )
) { Current = "0"; };
};
document.Calculator.Display.value = Current;
}
function Clear() //CLEAR ENTRY
{ Current = "0";
document.Calculator.Display.value = Current;
}
function AllClear() //Clear ALL entries!
{ Current = "0";
Operation = 0; //clear operation
Memory = "0"; //clear memory
document.Calculator.Display.value = Current;
}
function Operate(op) //STORE OPERATION e.g. + * / etc.
{
if (Operation != 0) { Calculate(); }; //'Press "=" if pending operation!
// note that design is not good for showing *intermediate* results.
if (op.indexOf("*") > -1) { Operation = 1; }; //codes for *
if (op.indexOf("/") > -1) { Operation = 2; }; // slash (divide)
if (op.indexOf("+") > -1) { Operation = 3; }; // sum
if (op.indexOf("-") > -1) { Operation = 4; }; // difference
Memory = Current; //store value
// note how e.g. Current.value gives neither error nor value! ***
Current = "";
document.Calculator.Display.value = Current;
}
function Calculate() //PERFORM CALCULATION (= button)
{
if (Operation == 1) { Current = eval(Memory) * eval(Current); };
if (Operation == 2)
{ if (eval(Current) != 0)
{ Current = eval(Memory) / eval(Current)
} else
{ Current = "Aargh! Divide by zero"; //don't allow over MAXLENGTH digits before "." ???
}
};
if (Operation == 3) { Current = eval(Memory) + eval(Current); };
if (Operation == 4) { Current = eval(Memory) - eval(Current); };
Operation = 0; //clear operation
Memory = "0"; //clear memory
Current = Current + ""; //FORCE A STRING!
if (Current.indexOf("Infinity") != -1) //eg "1e320" * 1
{ Current = "Aargh! Value too big";
};
if (Current.indexOf("NaN") != -1) //eg "1e320" / "1e320"
{ Current = "Aargh! I don't understand";
};
document.Calculator.Display.value = Current;
// NOTE: if no operation, nothing changes, Current is left the same!
}
function FixCurrent()
{
Current = document.Calculator.Display.value;
Current = "" + parseFloat(Current);
if (Current.indexOf("NaN") != -1)
{
Current = "Aargh! I don't understand";
};
document.Calculator.Display.value = Current;
}
//--------------------------------------------------------------->
</script>
</head>
<body>
*From <a href="http://www.anaesthetist.com/mnm/javascript/calc.htm">http://www.anaesthetist.com/mnm/javascript/calc.htm</a>
<FORM name="Calculator">
<table width="45%" border="4" bgcolor="#9999CC"><tr> <!--OUTER MARGIN OF CALCULATOR-->
<td colspan="2" align="center">
<b><font face="Verdana, Arial, Helvetica" color="#000080" size="3">
A Simple JavaScript Calculator<br></font>
<font face="Courier" size="5">
<input type="text" maxlength="40" size="25" name="Display" onChange="FixCurrent()">
</font></b>
</td></tr>
<tr><td width="65%" align="center"> <!--left panel------>
<table><tr>
<td><input type="button" name="seven" value=" 7 " OnClick="AddDigit('7')"></td>
<td><input type="button" name="eight" value=" 8 " OnClick="AddDigit('8')"></td>
<td><input type="button" name="nine" value=" 9 " OnClick="AddDigit('9')"></td>
</tr><tr>
<td><input type="button" name="four" value=" 4 " OnClick="AddDigit('4')"></td>
<td><input type="button" name="five" value=" 5 " OnClick="AddDigit('5')"></td>
<td><input type="button" name="six" value=" 6 " OnClick="AddDigit('6')"></td>
</tr><tr>
<td><input type="button" name="one" value=" 1 " OnClick="AddDigit('1')"></td>
<td><input type="button" name="two" value=" 2 " OnClick="AddDigit('2')"></td>
<td><input type="button" name="three" value=" 3 " OnClick="AddDigit('3')"></td>
</tr><tr>
<td><input type="button" name="plusmin" value=" +/- " OnClick="PlusMinus()"></td>
<td><input type="button" name="one" value=" 0 " OnClick="AddDigit('0')"></td>
<td><input type="button" name="two" value=" . " OnClick="Dot()"></td>
</tr>
</table>
</td> <!--end left panel-->
<td width="35%" align="center"> <!--right panel----->
<table><tr>
<td><input type="button" name="clear" value=" C " OnClick="Clear()"></td>
<td><input type="button" name="AC" value=" AC " OnClick="AllClear()"></td>
</tr><tr>
<td><input type="button" name="mul" value=" * " OnClick="Operate('*')"></td>
<td><input type="button" name="div" value=" / " OnClick="Operate('/')"></td>
</tr><tr>
<td><input type="button" name="add" value=" + " OnClick="Operate('+')"></td>
<td><input type="button" name="sub" value=" - " OnClick="Operate('-')"></td>
</tr><tr>
<td><input type="button" name="result" value=" = " OnClick="Calculate()"></td>
<td align="right"><input type="button" name="exp" value=" EXP " OnClick="DoExponent()"></td>
</tr></table>
</td> <!--end right panel-->
</tr></table> <!--END OUTER MARGIN CALC------->
</FORM></div>
</body>
</html>
@netantho
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Best JS code ever!

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