Introduction to the use of Javascript rounding Math.round() and Math.pow()

Author：Eve Cole Update Time：2025-01-26 13:48:01

Copy the code code as follows:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<head>

<title>Javascript rounding (Math.round() and Math.pow())</title>

//Math.round(x); Returns the nearest integer of the number, rounding to the integer, that is, discarding the decimal part

function f(){

alert(Math.round(123.567));

alert(Math.round(123.456));

}

//Math.pow(x,y); returns the specified power of the base

//Returns the numerical expression equal to x raised to the y power with x raised to the y power

//If the parameter of pow is too large and causes floating point overflow, return Infinity

function f1(){

alert(Math.pow(2,10));//2 raised to the 10th power is equal to 1024

alert(Math.pow(1024,0.1));//1024 raised to the power of 0.1 is equal to 2

alert(Math.pow(99,9999));//If overflow returns Infinity

}

/*Javascript sets the number of decimal places to be retained and rounded.

*ForDight(Dight,How): Numeric formatting function, the number to be formatted by Dight, and the number of decimal places to be retained by How.

*The method here is to first multiply by a multiple of 10, then remove the decimals, and finally divide by a multiple of 10.

function ForDight(Dight,How){

Dight = Math.round(Dight*Math.pow(10,How))/Math.pow(10,How);

return Light;

}

function f2(){

alert(ForDight(12345.67890,3));//retain three decimal places

alert(ForDight(123.99999,4));//retain four decimal places

}

//Another rounding method, the principle is the same.

//The two parameters inside: num are the data to be converted. n is the number of digits to be converted

//cheng(123.456,2);//retain two decimal places

function cheng(num,n){

vardd=1;

vartempnum;

for(i=0;i<n;i++){

dd*=10;

}

tempnum = num*dd;

tempnum = Math.round(tempnum);

alert(tempnum/dd);

}

</script>

</head>

<body>

</body>

</html>