JS - numerical processing (rounding, rounding, random numbers, etc.)

One . Keep the data

1.1 Keep only the integer parts

parseInt(1.23456)		// 1

1.2 Rounding down

Math.floor(1.23456)		// 1

1.3 Rounding up

Math.ceil(1.23456)		// 2

1.4 rounding

Math.round(1.23456)		// 1
Math.round(1.73456)		// 2

1.5 Take the absolute value

Math.abs(-1)			// 1

1.6 Take the larger of the two numbers

Math.max(3,2)			// 3

1.7 Take the smaller of two numbers

Math.min(3,2)			// 2

Two . random number

2.1 random number （0 - 1）

contain 0, It doesn't contain 1

Math.random();

2.2 Random integers

Math.random() And Math.floor() Use it together , Returns a random integer

• 0 to 10 （ contain 0, It doesn't contain 10）

  Math.floor(Math.random() * 10)
  

• 1 to 10 （ contain 1、10）

  Math.floor(Math.random() * 10) + 1
  

2.3 A random integer between two numbers

• contain min , It doesn't contain max

  function getRandomNum(min, max) {
        
  	return Math.floor(Math.random() * (max - min) ) + min;
  }
  getRandomNum(1,2)  // contain  1 , It doesn't contain  2
  

• contain min and max

  function getRandomNum(min, max) {
        
  	return Math.floor(Math.random() * (max - min + 1) ) + min;
  }
  getRandomNum(1,2)  // contain  1、2