DEV Community

Generating Random Whole numbers in JavaScript in a specific range

Sh Raj on January 14, 2022

Video Documentation :- https://youtu.be/xz3VbIaEG8o Mozilla Developer Network page on this JavaScript Math Object: https://developer.mozilla.o...

Read full post

Jon Randy 🎖️ • Jan 14 '22

About 40% faster:

const getRandomInt = (min, max)=>~~(Math.random()*(max-min+1)+min)

𒎏Wii 🏳️‍⚧️ • Jan 14 '22

It's faster because it doesn't work; at least not for numbers bigger than what fits in a 32-bit integer ;)

Jon Randy 🎖️ • Jan 14 '22

Poorly written spec ;)

𒎏Wii 🏳️‍⚧️ • Jan 14 '22

The spec is wrong 😝

Sh Raj • Jan 14 '22

Can You Minify this Function also...

function getParameterByName( name ){
  name = name.replace(/[\[]/,"\\\[").replace(/[\]]/,"\\\]");
  var regexS = "[\\?&]"+name+"=([^&#]*)";
  var regex = new RegExp( regexS );
  var results = regex.exec( window.location.href );
  if( results == null )
    return "";
  else
    return decodeURIComponent(results[1].replace(/\+/g, " "));
}

𒎏Wii 🏳️‍⚧️ • Jan 14 '22 • Edited

No need, your browser already minified it for you and put it in a class called URLSearchParams 😝

Sh Raj • Jan 14 '22

Ya bro it helped 💖

Damian Żygadło • Jan 15 '22

This is soooo confusing. I have like zero idea, why this works, espencially the "~" operator.

When I do ~(-1), I got 0, but if I do ~~(-1), I got -1. emm.... what?

codingjlu • Jan 17 '22

>> and | also work in flooring a number, but in negative values it rounds "down".

Jon Randy 🎖️ • Jan 17 '22

It isn't flooring in these cases - merely removing the decimal part.

codingjlu • Jan 17 '22

Oh, I forgot to mention—it behaves just like Math.floor unless the value is negative.

Jon Randy 🎖️ • Jan 15 '22 • Edited

~ is the bitwise NOT operator, which will reverse all bits in the number - having converted it to a 32-bit signed integer first. Applying it twice resets the bits to their original state. It's a dirty trick to convert to an integer

w3schools.com/js/js_bitwise.asp