JS_math_number.js

Number.isInteger()

  Number.isInteger(42);
  //=> true

  Number.isInteger(0.42);
  //=> false
------------------------------
Number.isFinite()
      Number.isFinite(9001);
  //=> true

    Number.isFinite(Infinity);
  //=> false
-------------------------------
  
  Number.isNaN()

    Number.isNaN(10);
    //=> false

    Number.isNaN(undefined);
    //=> false

    Number.isNaN(NaN);
    //=> true
--------------------------------

Number.parseInt()
#Accepts a string as its first argument and parses it as an integer. 
#The second argument is the base that should be used in parsing (e.g., 2 for binary or 10 for decimal).
#For example, 100 is 100 in decimal but 4 in binary:

    Number.parseInt('100', 10);
    //=> 100

    Number.parseInt('100', 2);
    //=> 4
--------------------------------------

Number.parseFloat()
#Number.parseFloat() only accepts a single argument, the string 
#that should be parsed into a floating-point number:

Number.parseFloat('3.14159');
//=> 3.14159

---------------------------------------
  
  Math.ceil() / Math.floor() / Math.round()
#JavaScript provides three methods for rounding numbers. Math.ceil() rounds the number up, 
#Math.floor() rounds the number down, 
#and Math.round() rounds the number either up or down, whichever is nearest:

      Math.ceil(0.5);
      //=> 1

      Math.floor(0.5);
      //=> 0

      Math.round(0.5);
      //=> 1

      Math.round(0.49);
      //=> 0
----------------------------------------
Math.max() / Math.min()
#These two methods accept a number of arguments and return the lowest 
#and highest constituent, respectively:

      Math.max(1, 2, 3, 4, 5);
      //=> 5

      Math.min(1, 2, 3, 4, 5);
      //=> 1
----------------------------------------
Math.random()
#This method generates a random number between 0 (inclusive) and 1 (exclusive):

Math.random();
//=> 0.4495507082209371
#In combination with some simple arithmetic and one of the rounding methods, we can 
#generate random integers within a specific range. For example, to generate a random integer between 1 and 10:

Math.floor(Math.random() * 10) + 1;
//=> 8
 
Math.floor(Math.random() * 10) + 1;
//=> 1
 
Math.floor(Math.random() * 10) + 1;
//=> 6
#Math.random() returns a number between 0 and 0.999..., which we multiply 
#by 10 to give us a number between 0 and 9.999.... We then pass that number to Math.floor(), which 
#returns an integer between 0 and 9. That's one less than the desired range (1 to 10), so we add one 
#at the end of the equation. Try it out in the JS console!