Example of method for generating random numbers in js_javascript skills

JS mainly uses the random() method of the built-in Math object to generate random numbers. Usage such as: Math.random(). It returns a random number between 0 and 1. With such a method, it is easy to understand how to generate arbitrary random numbers. For example, in practice we may have the following needs:
(1) Generate a random integer between 0 - 100 , then you can:

parseInt(100*Math.random()); 

Note: Because the return value of Math.random() includes 0 and 1, there is a possibility of generating 0 and 100 here.
(2) Generate a random integer from m - n . For example, to generate a random number between 5 - 15, you can:

parseInt(Math.random()*(15-5+1) + 5); 

In summary:

parseInt(Math.random()*(n-m+1)+m);//生成一个从 m - n 之间的随机整数

In addition, two other commonly used methods are summarized as needed, as follows:
(3) Generate a random integer with specified number of digits

function randomNum(n){ 
 var t=''; 
 for(var i=0;i<n;i++){ 
 t+=Math.floor(Math.random()*10); 
 } 
 return t; 
} 

(4) Generate a random integer within the specified range

function randomNum(minNum,maxNum){ 
 switch(arguments.length){ 
 case 1: 
  return parseInt(Math.random()*minNum+1); 
 break; 
 case 2: 
  return parseInt(Math.random()*(maxNum-minNum+1)+minNum); 
 break; 
 default: 
  return 0; 
 break; 
 } 
} 

For example, to generate a random integer between 2 and 9, then: randomNum(2,9); to generate a random integer between 1 and 22, then: randomNum(22)

The above is a summary of how to generate random numbers in js. I hope it will be helpful to everyone's learning.