Generating random integer JavaScript

I want to generate a random integer. When I enter a number in a textbox and call the function by clicking on a button, it says "The number was undefined", instead of giving the value of the generated number. Here is my code:

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

var array=[];
var integer=getRandomInt(1,100);
var broj=array[integer];