Preface :
JS does not have a ready-made function to generate a random number of the specified range directly.
But it has a function:math.random () This function can generate a random number of [0,1] .
With it, we can generate random numbers within a specified range.
When it comes to scope, there is a boundary value problem. This includes four scenarios:
1)Min≤r≤max (generally this is more common)
2) Min≤r < Max
3) Min < R≤max
4) Min < R < Max
First, 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;}
Second, Min≤r < Max
function Randomnum (Min, Max) {var Range = max-min; var Rand = Math.random (); var num = Min + math.floor (Rand * Range); to return num;}
Three, 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; }}
JS generates a range of random numbers (four cases)