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
Collapse
 
jonrandy profile image
Jon Randy πŸŽ–οΈ •

About 40% faster:

const getRandomInt = (min, max)=>~~(Math.random()*(max-min+1)+min)
Enter fullscreen mode Exit fullscreen mode
Collapse
 
darkwiiplayer profile image
π’ŽWii πŸ³οΈβ€βš§οΈ •

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

Collapse
 
jonrandy profile image
Jon Randy πŸŽ–οΈ •

Poorly written spec ;)

Thread Thread
 
darkwiiplayer profile image
π’ŽWii πŸ³οΈβ€βš§οΈ •

The spec is wrong 😝

Collapse
 
sh20raj profile image
Sh Raj •

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, " "));
}
Enter fullscreen mode Exit fullscreen mode
Collapse
 
darkwiiplayer profile image
π’ŽWii πŸ³οΈβ€βš§οΈ • • Edited

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

Thread Thread
 
sh20raj profile image
Sh Raj •

Ya bro it helped πŸ’–

Collapse
 
neoprint3d profile image
Drew Ronsman •

Never seen that way I will have to try and use it

Collapse
 
willaiem profile image
Damian Ε»ygadΕ‚o •

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?

Collapse
 
codingjlu profile image
codingjlu •

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

Thread Thread
 
jonrandy profile image
Jon Randy πŸŽ–οΈ •

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

Thread Thread
 
codingjlu profile image
codingjlu •

Oh, I forgot to mentionβ€”it behaves just like Math.floor unless the value is negative.

Collapse
 
jonrandy profile image
Jon Randy πŸŽ–οΈ • • 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

Collapse
 
sh20raj profile image
Sh Raj •

Thanks bro... πŸ‘πŸ‘
I will add this code to this Article πŸ‘πŸ‘

Collapse
 
codingjlu profile image
codingjlu •

The "minified" form doesn't behave the same. In negative numbers, the first function is inclusive, while the second one is exclusive.

Run both about 30 times to see what I mean, and pass the values -10, -1.