Js provides the corresponding function, that is, the fixed (n) method. Parameter n indicates how many decimal places are reserved.

For example:

var？ Answer? = 123.456789;

alert(a . to fixed(4))； //? Round to four decimal places.

//? Rounds a number and truncates n decimal places.

getResult(num，n)？ {

Return? Fixed quantity (n);

} Note:

What time? Throw an exception when n is too small or too large? Range error. Normal range is.

When the object calling this method is not. Number? When you throw it? TypeError？ Not normal.