js除法四舍五入

时间:2022-05-31 00:44:06
 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>floatDecimal.html</title>
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="this is my page">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<script type="text/javascript">
//保留两位小数
//功能:将浮点数四舍五入,取小数点后2位
function toDecimal(x) {
var f = parseFloat(x);
if (isNaN(f)) {
return;
}
f = Math.round(x*100)/100;
return f;
}
//制保留2位小数,如:2,会在2后面补上00.即2.00 function toDecimal2(x) {
var f = parseFloat(x);
if (isNaN(f)) {
return false;
}
var f = Math.round(x*100)/100;
var s = f.toString();
var rs = s.indexOf('.');
if (rs < 0) {
rs = s.length;
s += '.';
}
while (s.length <= rs + 2) {
s += '0';
}
return s;
} function fomatFloat(src,pos){
return Math.round(src*Math.pow(10, pos))/Math.pow(10, pos);
} //四舍五入
alert("保留2位小数:" + toDecimal(3.14159267));
alert("强制保留2位小数:" + toDecimal2(3.14159267));
alert("保留2位小数:" + toDecimal(3.14559267));
alert("强制保留2位小数:" + toDecimal2(3.15159267));
alert("保留2位小数:" + fomatFloat(3.14559267, 2));
alert("保留1位小数:" + fomatFloat(3.15159267, 1));
//五舍六入
alert("保留2位小数:" + 1000.003.toFixed(2));
alert("保留1位小数:" + 1000.08.toFixed(1));
alert("保留1位小数:" + 1000.04.toFixed(1));
alert("保留1位小数:" + 1000.05.toFixed(1));
//科学计数
alert(3.1415.toExponential(2));
alert(3.1455.toExponential(2));
alert(3.1445.toExponential(2));
alert(3.1465.toExponential(2));
alert(3.1665.toExponential(1));
//精确到n位,不含n位
alert("精确到小数点第2位" + 3.1415.toPrecision(2));
alert("精确到小数点第3位" + 3.1465.toPrecision(3));
alert("精确到小数点第2位" + 3.1415.toPrecision(2));
alert("精确到小数点第2位" + 3.1455.toPrecision(2));
alert("精确到小数点第5位" + 3.141592679287.toPrecision(5));
</script>
</head>
<body>
This is my HTML page. <br>
</body>
</html>