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js四则运算
有两个文本框，如何在一个文本框中输入四则表达式:4*34-56*5，可以不带括号，第二个表达式自动得出结果，使用js实现，谢谢了
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qingYun1029 2009-12-22
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测试成功！！！
<!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=gb2312" />
<title>无标题文档</title>
<script type="text/javascript" language="javascript">
function Sum()
{
var a = eval(document.getElementById("txtA").value);
document.getElementById("txtB").value = a;
}
</script>
</head>
<body>
<input type="text" id="txtA" />
<input type="text" id="txtB" />
<input type="button" value=" 计 算 " onclick="Sum()" />
</body>
</html>
<!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=gb2312" />
<title>无标题文档</title>
<script type="text/javascript" language="javascript">
function Sum()
{
var a = eval(document.getElementById("txtA").value);
document.getElementById("txtB").value = a;
}
</script>
</head>
<body>
<input type="text" id="txtA" />
<input type="text" id="txtB" />
<input type="button" value=" 计 算 " onclick="Sum()" />
</body>
</html>
郭大侠_ 2009-12-22
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<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>新建网页 1</title>
<script type="text/javascript">
function calc()
{
document.getElementById("txt2").value=eval("("+ document.getElementById("txt1").value +")");
}
</script>
</head>
<body>
<input id="txt1" value="4*34-56*5" />
<input type="button" value="计算" onclick="calc();" />
<input id="txt2" value="" />
</body>
</html>Inpool 2009-12-22
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text1.onkeyup = function(){text2.value = eval(text1.value);}
ACMAIN_CHM 2009-12-22
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eval("4*34-56*5")