Multiply-and-divide.

For example, to round the number to the 2nd digit after the decimal, we can multiply the number by 100, call the rounding function and then divide it back.

let num = 1.23456;alert( Math.round(num * 100) / 100 ); // 1.23456 -> 123.456 -> 123 -> 1.23

In the documentation you mentioned two ways to reduce the the number of decimal places. However, the first method can give inconsistent results because of the Math.round() method.

for example if the number is 1.23567
the result will be 1.24 instead of 1.23

let num = 1.23567;alert( Math.round(num * 100) / 100 ); // 1.23456 -> 123.456 -> 124 -> 1.24