JavaScript generate random number except some values

Question

I\'m generating random numbers from 1 to 20 by calling generateRandom(). How can I exclude some values, say 8 and 15?

function generateRandom(mi         


        

Answer 1

it should be or instead of and

function generateRandom(min, max) {
    var num = Math.floor(Math.random() * (max - min + 1)) + min;
    return (num === 8 || num === 15) ? generateRandom(min, max) : num;
}

var test = generateRandom(1, 20)

Answer 2

This is a simple and neat idea, I am a electromechanical engineer and I am just learning JS. This is going to print a random numeber between 1 and 100. Except 8 and 15

 var r;   // this is the random integer.
 var val; //this will serve as validator for the random integer.

 val=0; 
 while(val==0)    {
 r=Math.round(Math.random()*100)+1;
 if(r!=8 && r!=15){val=1;}    //a valid number will be any number different from 8 and 15
                              //then validator will change and go out from the loop.
                }   
document.write(r);

Answer 3

Right now I'm using this and it works without causing browser issues with infinities loops, also tested in mobile devices (using Ionic/Cordova):

function getRandomIndex(usedIndexs, maxIndex) {
    var result = 0;
    var min = 0;
    var max = maxIndex - 1;
    var index = Math.floor(Math.random()*(max-min+1)+min);

    while(usedIndexs.indexOf(index) > -1) {
        if (index < max) {
            index++;
        } else {
          index = 0;
        }
    }

    return index;
}

Answer 4

I think it should be like this, if you want good distribution on all numbers. and, for this solution, it is required to higher max than 15 and lower min that 8

function generateRandom(min, max) {
    var v =  Math.floor(Math.random() * (max - min + 1 - 2)) + min;
    if (v == 8) return max-1;
    else if (v == 15) return max-2;
    else return v;
}

var test = generateRandom(1, 20)

Answer 5

You could make use of a recursive function

function generateRandom(min, max, num1, num2) {
    var rtn = Math.floor(Math.random() * (max - min + 1)) + min;
    return rtn == num1 || rtn == num2 ? generateRandom(min, max, num1, num2) : rtn;
}

Answer 6

You can build an array dynamically. Depending on where you are getting the excluded numbers. Something like:

var excluded = [8, 15];
var random = [];
for(var i = min; i <= max; i++) {
  if(excluded.indexOf(i) !== -1) {
    random.push(i);
  }
}

Then use the tips found in the answer for this post: How can I generate a random number within a range but exclude some?. Should get you to where you want to go.