Javascript generates random numbers in a specific range. [four details] _ javascript tips-JS tutorial

The following small series will bring you an article on how to generate a random number in a specific range in JS [four situations ]. I think this is quite good. Now I will share it with you and give you a reference. Let's take a look at the preface:

JS does not have ready-made functions and can directly generate random numbers within a specified range.

However, it has a function: Math. random (), which can generate a random number of [0, 1.

With this, we can generate a random number within the specified range.

If the range is involved, there is a boundary value problem. In this way, there are four situations:

1) min ≤ r ≤ max (this is common)

2) min ≤ r <max

3) min <r ≤ max

4) min <r <max

1. min ≤ r ≤ max

Function RandomNumBoth (Min, Max) {var Range = Max-Min; var Rand = Math. random (); var num = Min + Math. round (Rand * Range); // rounding return num ;}

2. min ≤ r <max

Function RandomNum (Min, Max) {var Range = Max-Min; var Rand = Math. random (); var num = Min + Math. floor (Rand * Range); // return num ;}

3. min <r ≤ max

function RandomNum(Min, Max) {      var Range = Max - Min;      var Rand = Math.random();      if(Math.round(Rand * Range)==0){               return Min + 1;      }      var num = Min + Math.round(Rand * Range);      return num;}

Iv. min <r <max

function RandomNum(Min, Max) {      var Range = Max - Min;      var Rand = Math.random();      if(Math.round(Rand * Range)==0){        return Min + 1;      }else if(Math.round(Rand * Max)==Max)      {        index++;        return Max - 1;      }else{        var num = Min + Math.round(Rand * Range) - 1;        return num;      } }

The above JS generates a random number in a certain range [four situations] is all the content shared by Alibaba Cloud xiaobian. I hope you can give us a reference and support for me.