贵族学校的神秘公主:用javascript编写计算器

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用JAVascript怎洋实现计算器功能要求能做简单的+，-，*，/和Sqr运算

用javascript编写计算器:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Javascript实现计算器</title>
<style type="text/css">
input{
width:30px;
height:20px;
text-align:center;
}
#tbCalculator td
{
text-align:center;
vertical-align:middle;
}
</style>
<script type="text/javascript">
var result; //保存点击运算符之前输入框中的数值
var operator; //保存运算符
var isPressEqualsKey = false; //记录是否按下”=“键
//数字键事件
function connectionDigital(control)
{
var txt = document.getElementById('txtScream');
if(isPressEqualsKey)
{ 
txt.value = ""; //已进行过计算，则清空数值输入框重新开始
isPressEqualsKey = false;
}
//数值输入已经存在小数点,则不允许再输入小数点
if(txt.value.indexOf('.') > -1 && control.value == '.')
return false;
txt.value += control.value; //将控件值赋给数值输入框中
}
//退格键事件
function backspace()
{
var txt = document.getElementById('txtScream');
txt.value = txt.value.substring(0,txt.value.length - 1);
}
//ce键事件：清空数字输入框
function clearAll()
{
document.getElementById('txtScream').value = "";
result = "";
operator = "";
}
// +、-、*、/ 事件
function calculation(control)
{
//将运算符保存入全局变量中
operator = control.value; 
var txt = document.getElementById('txtScream');
if(txt.value == "")return false; //数值输入框中没有数字，则不能输入运算符
//将数值输入框中的值保存到计算表达式中
result = txt.value; 
//清空输入框，以待输入操作值
txt.value = ""; 
}
//计算结果
function getResult()
{
var opValue;
//计算表达式中存在运算符
var sourseValue = parseFloat(result);
var txt = document.getElementById('txtScream');
if(operator == '*')
opValue = sourseValue * parseFloat(txt.value);
else if(operator == '/')
opValue = sourseValue / parseFloat(txt.value);
else if(operator == '+')
opValue = sourseValue + parseFloat(txt.value);
else if(operator == '-')
opValue = sourseValue - parseFloat(txt.value);
txt.value = opValue;
isPressEqualsKey = true;
result = "";
opValue = "";
}
</script>
</head>
<body>
<table id="tbCalculator" width="200" border="1" align="center" cellpadding="0" cellspacing="0" bordercolor="#0066FF">
<tr>
<td height="30" colspan="4" align="center">
<input type="text" name="txtScream" id="txtScream" style="width:180px; border-style:none; text-align:right;" readonly="readonly" /> </td>
</tr>
<tr>
<td height="30" colspan="2">
<input type="button" name="btnCE" id="btnCE" value="C&nbsp;E" style="width:80px;" align="right"; onclick="clearAll();" /></td>
<td height="30" colspan="2">
<input type="button" name="btn10" id="btn10" value="Backspace" style="width:80px;" align="right"; onclick="backspace();" /></td>
</tr>
<tr>
<td height="30"><input type="button" name="btn7" id="btn7" value="7" onclick="connectionDigital(this);" /></td>
<td><input type="button" name="btn8" id="btn8" value="8" onclick="connectionDigital(this);"/></td>
<td><input type="button" name="btn9" id="btn9" value="9" onclick="connectionDigital(this);" /></td>
<td><input type="button" name="btn6" id="btn6" value="/" onclick="calculation(this);" /></td>
</tr>
<tr>
<td height="30">
<input type="button" name="btn4" id="btn4" value="4" onclick="connectionDigital(this);"/></td>
<td><input type="button" name="btn5" id="btn5" value="5" onclick="connectionDigital(this);"/></td>
<td><input type="button" name="btn6" id="btn6" value="6" onclick="connectionDigital(this);"/></td>
<td><input type="button" name="btn13" id="btn13" value="*" onclick="calculation(this);" /></td>
</tr>
<tr>
<td height="30">
<input type="button" name="btn1" id="btn1" value="1" onclick="connectionDigital(this);"/></td>
<td><input type="button" name="btn2" id="btn2" value="2" onclick="connectionDigital(this);"/></td>
<td><input type="button" name="btn3" id="btn3" value="3" onclick="connectionDigital(this);"/></td>
<td><input type="button" name="btn18" id="btn18" value="-" onclick="calculation(this);" /></td>
</tr>
<tr>
<td height="30"><input type="button" name="btn0" id="btn0" value="0" onclick="connectionDigital(this);"/></td>
<td><input type="button" name="btndot" id="btndot" value="." onclick="connectionDigital(this);" /></td>
<td><input name="btn22" type="button" id="btn22" value="=" onclick="getResult();" /></td>
<td><input type="button" name="btn23" id="btn23" value="+" onclick="calculation(this);" /></td>
</tr>
</table>
</body>
</html>

一个与windowsl类似的计算器

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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