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<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>Javascript rounded (Math.round() with Math.pow())</title>
<script type="text/javascript">
//Math. Round (x); Returns the nearest integer to the number, rounded to the integer, that is, to the decimal part
function f(){
alert(Math.round(123.567));
alert(Math.round(123.456));
}
//Math.h pow (x, y); Returns the specified power of the base
//Returns a numerical expression in terms of x to the y, equal to x to the y
//Returns Infinity if the pow parameter is too large and causes floating point overflow
function f1(){
alert(Math.pow(2,10));//2 to the 10th is equal to 1024
alert(Math.pow(1024,0.1));//1024 to the 0.1 power is equal to 2
alert(Math.pow(99,9999));//Overflow returns Infinity
}
function ForDight(Dight,How){
Dight = Math.round(Dight*Math.pow(10,How))/Math.pow(10,How);
return Dight;
}
function f2(){
alert(ForDight(12345.67890,3));//Three decimal places
alert(ForDight(123.99999,4));//Keep the four decimal places
}
//Another way to round it is the same principle.
//Num is the data to be converted. N is the number of bits to be converted
//cheng(123.456,2);// Keep two decimal places
function cheng(num,n){
var dd=1;
var tempnum;
for(i=0;i<n;i++){
dd*=10;
}
tempnum = num*dd;
tempnum = Math.round(tempnum);
alert(tempnum/dd);
}
</script>
</head>
<body>
<input type="button" value="round" onclick="f();" />
<input type="button" value="pow" onclick="f1();" />
<input type="button" value=" Sets the number of decimal places to keep, rounding " onclick="f2();" />
<input type="button" value="cheng" onclick="cheng(123.456,2);" />
</body>
</html>