trully random integers using javascript

Question

I'm using the following code

function getRandomInt(min, max) {
    return Math.floor(Math.random() * (max - min + 1)) + min;
}

to come up with a random number. However, this is not giving me a random distribution. Does anyone know a better way to come up with a random number in javascript?

How do you know it's not giving you a random distribution? Did you perform a chi-square test on the results? How many times did you call it? — Barmar, Feb 15 '17 at 23:48
You've an extra parenthesis in your source - it won't compile. Presumably it's the second one in `.random())`, otherwise what @TamasHegedus says applies — CupawnTae, Feb 15 '17 at 23:53

score 0 · Answer 1 · answered Feb 15 '17 at 23:54

You have an error in your code, Math.floor(Math.random()) * should be Math.floor(Math.random() *. That aside, if you look at a large enough sample size, for example 100,000, it looks pretty close to even to me.

function getRandomInt(min, max) {
    return Math.floor(Math.random() * (max - min + 1)) + min;
}

var total = 0, count = 100000;
for(var i = 0; i<count; i++){
  total += getRandomInt(1,100);
}

console.log("Expected: 50.5");
console.log("Actual: "+(total / count));

trully random integers using javascript

1 Answers1