Usage and related functions of generating random numbers in JS_javascript skills

First, let me introduce some related functions about random numbers:
var Rand = Math.random();

• 1.Math.random(); The result is a random number between 0-1 (including 0, excluding 1)
• 2.Math.floor(num); The parameter num is a numerical value, and the function result is the integer part of num.
• 3.Math.round(num); The parameter num is a numerical value, and the function result is the integer after num is rounded.

Math: Math object, providing mathematical calculations on data.
Math.random(); Returns a random number between 0 and 1 (including 0, excluding 1).

Math.ceil(n); Returns the smallest integer greater than or equal to n.
When using Math.ceil(Math.random()*10);, you mainly get random integers from 1 to 10, and the probability of getting 0 is very small.

Math.round(n); Returns the value of n rounded to an integer.
Use Math.round(Math.random()); to get a random integer from 0 to 1 evenly.
When using Math.round(Math.random()*10);, you can basically obtain random integers from 0 to 10 in a balanced manner, including the probability of obtaining the minimum value 0 and the maximum value 10 Less than half.

Math.floor(n); Returns the largest integer less than or equal to n.
When using Math.floor(Math.random()*10);, random integers from 0 to 9 can be obtained evenly.
Random lottery can also be expanded, such as setting the probability of lottery and using it with the database.

//中奖概率需求，100%中奖，有3项奖品，但是抽到书本的概率为20%
function draw() {
  var d_s = GetRandom(100);
  if (d_s >= 1 && d_s <= 40) {
    alert('恭喜您抽到XXX！');
  } else if (d_s >= 41 && d_s <= 80) {
    alert('恭喜您抽到XXX！');
  } else {
    alert('恭喜您抽到书本！');
  }
}

Corresponding js function code for generating random numbers:

<script> 
 2function GetRandomNum(Min,Max)
{  
  var Range = Max - Min;  
  var Rand = Math.random();  
  return(Min + Math.round(Rand * Range));  
}  
 8var num = GetRandomNum(1,10);  
 9alert(num);  
</script>

var chars = ['0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'];

function generateMixed(n) {
   var res = "";
   for(var i = 0; i < n ; i ++) {
     var id = Math.ceil(Math.random()*35);
     res += chars[id];
   }
   return res;
}

The above is the detailed content of this article, I hope it will be helpful to everyone’s study.