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JavaScript JavaScript Basics (Retired) Creating Reusable Code with Functions Random Number Challenge, Part II

Is this really efficient?

I am still playing with it, but after looking up loads of stuff on jsperf and across google this code runs faster than anything else I have come up with.

Dave McFarland

Edit: I will add the string check later (umm... to prevent "Bob" from being passed, or perhaps warning the user than using Bob in a numerical representation)

/*Functions*/
function getRandomNumberAfterCheck(top,bottom){
  return floor((Math.random() * (top - bottom + 1))) + bottom; 
}
function getRandomNumber(top,bottom) {
  return getRandomNumberAfterCheck(checkInt(top),checkInt(bottom));
}
function checkInt(num) {
  return num !== num ? num : ~~num;
}
function floor(num) { //This will only work for positive numbers....
  return num|0;
}

alert(getRandomNumber('100','98'));

2 Answers

Zoltán Holik
Zoltán Holik
3,401 Points

Yes it's efficient, but i have a better solution i think :)

function randomNumber(max, min){
        return Math.abs(~~((Math.random() * ( ~~max - ~~min + 1))) +  ~~min);
}

alert(randomNumber('100', '98'));

Test case: http://jsperf.com/javascript-random-test

Yeah I though of a few ways for negative numbers, it turns out this does work for extremely large numbers either... Also I found a few other faster random methods but I cannot get them to work properly.

Always fun to play with though!

wow