Rounding related calculation

Ah , Recently, it is because of a certain amount , Just a few customers , Let the development without internal confirmation , I have to change the amount back and forth , Okay . Give you some way to calculate the whole rounding .

1 Keep two decimal places toFixed（n）

 Round function  toFixed（）, The parameters inside   It's the number of decimal places .
let a=2.1512131231231321;  
console.log(a.toFixed(2)) // 2.15

2 Keep only the integer parts （ Discard the fraction ） parseInt（）

let a=2.1512131231231321;  
console.log(parseInt(a)) // 2

3 Rounding down （<= The maximum integer of the value , and parseInt() equally )

let a=2.1512131231231321;  
console.log(Math.floor(a)) // 2

4 Rounding up （ There are decimals , Integer part +1）

let a=2.1512131231231321;  
console.log(Math.ceil(a)) // 3

5 rounding （ The fractional part ）

let a=5.1234
console.log(Math.round(a)) // 5
let b = 5.6789
console.log(Math.round(b)) // 6

6 Take the absolute value

let b = -5.6789
console.log(Math.abs(b)) // 5.6789

7 Returns the larger of two numbers

Math.max(1,2);     // 2

8 Returns the smaller of two numbers

Math.min(1,2);    // 1

9 random number （0-1）

Math.random();

10 If you want random integers, just add a calculation method to them Math.random()*10

OK 了 , Welcome to correct .