| 要完成此效果需要两个步骤 第一步:把如下代码加入到<head>区域中 <style type="text/css"><!--
 body {font-family: helvetica}
 p {font-size: 12pt}
 .red {color: red}
 .blue {color: blue}
 -->
 </style>
 <SCRIPT LANGUAGE="JavaScript"><!-- Begin
 var Memory = 0;
 var Number1 = "";
 var Number2 = "";
 var NewNumber = "blank";
 var opvalue = "";
 function Display(displaynumber) {document.calculator.answer.value = displaynumber;
 }
 function MemoryClear() {Memory = 0;
 document.calculator.mem.value = "";
 }
 function MemoryRecall(answer) {if(NewNumber != "blank") {
 Number2 += answer;
 } else {
 Number1 = answer;
 }
 NewNumber = "blank";
 Display(answer);
 }
 function MemorySubtract(answer) {Memory = Memory - eval(answer);
 }
 function MemoryAdd(answer) {Memory = Memory + eval(answer);
 document.calculator.mem.value = " M ";
 NewNumber = "blank";
 }
 function ClearCalc() {Number1 = "";
 Number2 = "";
 NewNumber = "blank";
 Display("");
 }
 function Backspace(answer) {answerlength = answer.length;
 answer = answer.substring(0, answerlength - 1);
 if (Number2 != "") {
 Number2 = answer.toString();
 Display(Number2);
 } else {
 Number1 = answer.toString();
 Display(Number1);
 }
 }
 function CECalc() {Number2 = "";
 NewNumber = "yes";
 Display("");
 }
 function CheckNumber(answer) {if(answer == ".") {
 Number = document.calculator.answer.value;
 if(Number.indexOf(".") != -1) {
 answer = "";
 }
 }
 if(NewNumber == "yes") {
 Number2 += answer;
 Display(Number2);
 }
 else {
 if(NewNumber == "blank") {
 Number1 = answer;
 Number2 = "";
 NewNumber = "no";
 }
 else {
 Number1 += answer;
 }
 Display(Number1);
 }
 }
 function AddButton(x) {
 if(x == 1) EqualButton();
 if(Number2 != "") {
 Number1 = parseFloat(Number1) + parseFloat(Number2);
 }
 NewNumber = "yes";
 opvalue = '+';
 Display(Number1);
 }
 function SubButton(x) {
 if(x == 1) EqualButton();
 if(Number2 != "") {
 Number1 = parseFloat(Number1) - parseFloat(Number2);
 }
 NewNumber = "yes";
 opvalue = '-';
 Display(Number1);
 }
 function MultButton(x) {
 if(x == 1) EqualButton();
 if(Number2 != "") {
 Number1 = parseFloat(Number1) * parseFloat(Number2);
 }
 NewNumber = "yes";
 opvalue = '*';
 Display(Number1);
 }
 function DivButton(x) {
 if(x == 1) EqualButton();
 if(Number2 != "") {
 Number1 = parseFloat(Number1) / parseFloat(Number2);
 }
 NewNumber = "yes";
 opvalue = '/';
 Display(Number1);
 }
 function SqrtButton() {
 Number1 = Math.sqrt(Number1);
 NewNumber = "blank";
 Display(Number1);
 }
 function PercentButton() {
 if(NewNumber != "blank") {
 Number2 *= .01;
 NewNumber = "blank";
 Display(Number2);
 }
 }
 function RecipButton() {
 Number1 = 1/Number1;
 NewNumber = "blank";
 Display(Number1);
 }
 function NegateButton() {
 Number1 = parseFloat(-Number1);
 NewNumber = "no";
 Display(Number1);
 }
 function EqualButton() {
 if(opvalue == '+') AddButton(0);
 if(opvalue == '-') SubButton(0);
 if(opvalue == '*') MultButton(0);
 if(opvalue == '/') DivButton(0);
 Number2 = "";
 opvalue = "";
 }
 //  End -->
 </script>
 第二步:把如下代码加入到<body>区域中
 <center><form name="calculator">
 <table bgcolor="#aaaaaa" width=220>
 <tr><td>
 <table bgcolor="#cccccc" border=1>
 <tr><td>
 <table border=0 cellpadding=0>
 <tr>
 <td bgcolor="#000080">
 <div align="center"><b style="color:white">JavaScript Fairyland</b></div>
 </td>
 </tr>
 <tr><td>
 <table width="100%" border=0>
 <tr><td colspan=6><input type="text" name="answer" size=30 maxlength=30 onChange="CheckNumber(this.value)"></td></tr>
 <tr><td colspan=6>
 <table border=0 cellpadding=0>
 <tr><td>
 <input type="text" name="mem" size=3 maxlength=3> <input type="button" name="backspace" class="red" value="Backspace" onClick="Backspace(document.calculator.answer.value); return false;"> <input type="button" name="CE" class="red" value=" CE " onClick="CECalc(); return false;"> <input type="reset" name="C" class="red" value="  C  " onClick="ClearCalc(); return false;">
 </td></tr>
 </table>
 </td></tr>
 <tr><td><input type="button" name="MC" class="red" value=" MC " onClick="MemoryClear(); return false;"></td>
 <td><input type="button" name="calc7" class="blue" value="  7  " onClick="CheckNumber('7'); return false;"></td>
 <td><input type="button" name="calc8" class="blue" value="  8  " onClick="CheckNumber('8'); return false;"></td>
 <td><input type="button" name="calc9" class="blue" value="  9  " onClick="CheckNumber('9'); return false;"></td>
 <td><input type="button" name="divide" class="red" value="  /  " onClick="DivButton(1); return false;"></td>
 <td><input type="button" name="sqrt" class="blue" value="sqrt" onClick="SqrtButton(); return false;"></td></tr>
 <tr><td><input type="button" name="MR" class="red" value=" MR " onClick="MemoryRecall(Memory); return false;"></td>
 <td><input type="button" name="calc4" class="blue" value="  4  " onClick="CheckNumber('4'); return false;"></td>
 <td><input type="button" name="calc5" class="blue" value="  5  " onClick="CheckNumber('5'); return false;"></td>
 <td><input type="button" name="calc6" class="blue" value="  6  " onClick="CheckNumber('6'); return false;"></td>
 <td><input type="button" name="multiply" class="red" value="  *  " onClick="MultButton(1); return false;"></td>
 <td><input type="button" name="percent" class="blue" value=" %  " onClick="PercentButton(); return false;"></td></tr>
 <tr><td><input type="button" name="MS" class="red" value=" MS " onClick="MemorySubtract(document.calculator.answer.value); return false;"></td>
 <td><input type="button" name="calc1" class="blue" value="  1  " onClick="CheckNumber('1'); return false;"></td>
 <td><input type="button" name="calc2" class="blue" value="  2  " onClick="CheckNumber('2'); return false;"></td>
 <td><input type="button" name="calc3" class="blue" value="  3  " onClick="CheckNumber('3'); return false;"></td>
 <td><input type="button" name="minus" class="red" value="  -  " onClick="SubButton(1); return false;"></td>
 <td><input type="button" name="recip" class="blue" value="1/x " onClick="RecipButton(); return false;"></td></tr>
 <tr><td><input type="button" name="Mplus" class="red" value=" M+  " onClick="MemoryAdd(document.calculator.answer.value); return false;"></td>
 <td><input type="button" name="calc0" class="blue" value="  0  " onClick="CheckNumber('0'); return false;"></td>
 <td><input type="button" name="negate" class="blue" value="+/- " onClick="NegateButton(); return false;"></td>
 <td><input type="button" name="dot" class="blue" value="  .   " onClick="CheckNumber('.'); return false;"></td>
 <td><input type="button" name="plus" class="red" value=" +  " onClick="AddButton(1); return false;"></td>
 <td><input type="button" name="equal" class="red" value="  =   " onClick="EqualButton(); return false;"></td>
 </tr>
 </table>
 </td></tr>
 </table>
 </td></tr>
 </table>
 </td></tr>
 </table>
 </form>
 </center>
 
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