convert HEX to RGB

annotated.js

function(
  a                  // take a "#xxxxxx" hex string,
){
  a = +(             // turn it into a number by taking the
    "0x" +           // hexadecimal prefix and the
    a.slice(1)       // numerical portion,
    .replace(        // and
      a.length > 4   // if the #xxxxxx form is used
        && /./g,     // replace each character
      '$&$&'         // with itself twice.
    )
  );

  return [        // return an array
    a >> 16,      // with red,
    a >> 8 & 255, // blue,
    a & 255       // and green components.
  ]
}

index.js

function(a){a='0x'+a.slice(1).replace(a.length>4&&/./g,'$&$&');return[a>>16,a>>8&255,a&255]}

LICENSE.txt

            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
                    Version 2, December 2004

 Copyright (C) 2011 Jed Schmidt <http://jed.is>

 Everyone is permitted to copy and distribute verbatim or modified
 copies of this license document, and changing it is allowed as long
 as the name is changed.

            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

  0. You just DO WHAT THE FUCK YOU WANT TO.

package.json

{
  "name": "hex2rgb",

  "description": "Converts a hex string to RGB.",

  "keywords": [
    "hex",
    "color",
    "rgb" 
  ]
}

If you're assuming the arg is a proper hex with hash prefix, why not just this?
x=function(h){return['0x'+h[1]+h[2]|0,'0x'+h[3]+h[4]|0,'0x'+h[5]+h[6]|0]}

@kuvos Nice! Unfortunately it seems to return incorrect results for "#abc": [171,0,0] instead of [170,187,204]. Typo?

yeah, i'm pretty sure that only works for 6-digit strings.

…

On Tue, May 24, 2011 at 11:43 AM, mathiasbynens ***@***.*** wrote: @kuvos Nice! Unfortunately it seems to return incorrect results for "#abc": `[171,0,0]` instead of `[170,187,204]`. ## Reply to this email directly or view it on GitHub: https://gist.github.com/983661

Here’s @kuvos’ solution, with added support for shorthand hex values:

function(h){h[4]||(h=h.replace(/./g,'$&$&').slice(1));return['0x'+h[1]+h[2]|0,'0x'+h[3]+h[4]|0,'0x'+h[5]+h[6]|0]}

113 bytes, so comment #32248 still wins for now.

ah, yes mine was meant to replace the original :p

Another variation of @kuvos’ solution (100 bytes):

function(h,b){b=h[4];return['0x'+h[1]+h[b?2:1]|0,'0x'+h[b?3:2]+h[b?4:2]|0,'0x'+h[b?5:3]+h[b?6:3]|0]}

Caching '0x' doesn’t save any bytes:

function(h,b,x){x='0x';b=h[4];return[x+h[1]+h[b?2:1]|0,x+h[b?3:2]+h[b?4:2]|0,x+h[b?5:3]+h[b?6:3]|0]}

Comment #32248 still wins for now.

oh right, 'undefined' will be cut off anyways. nice. and yeah, caching '0x' or whatever doesnt matter

Here's a CoffeeScript version... I win (82 bytes)!

(a)->a=+("0x"+a[1..].replace(/^(.)(.)(.)$/,"$1$1$2$2$3$3"));[a>>16,a>>8&255,a&255]

88 bytes:

function(a){a='0x'+a.slice(1).replace(a[4]||/./g,'$&$&')|0;return[a>>16,a>>8&255,a&255]}

by the way, the @qfox trick of exploiting the low precedence of | is genius.

@jed Chrome and Safari throw parse errors for that last one...

Nevermind.

<-- @kuvos ;)

<-- @JedSchmidt ;)

<-- #knews ;) guess i need to thank twitter for screwing up my nickname some day.

@jed Wouldn’t that 88-byte version break on #abcdef strings? It would still duplicate a char, no?

94 bytes:

function(a){a='0x'+a.slice(1).replace(a[4]||/./g,a[4]||'$&$&')|0;return[a>>16,a>>8&255,a&255]}

i don't think so... if it's more than 3 digits, the regexp pattern magically turns to undefined, which doesn't match.

@jed

.replace(a[4]||/./g,a[4]||'$&$&')

If a[4] is undefined it means it’s a shorthand, and in that case the || kicks in and the regex replace takes place.

If a[4] is truthy it means it’s not a shorthand. The || will be ignored, and the replace would be similar to:

.replace(a[4],'$&$&')

In other words, the character at a[4] would be repeated. No?

here's what i had before, one more byte but safer:

a[4]?a:/./g

is that okay?

a wont match at this point because it still has the #

I’m confused as to how that would work… Wouldn’t that use the entire string a if a[4] is truthy (not a shorthand) and repeat it?

Oh, just saw your edit:

a wont match at this point because it still has the #.

Doh! Thanks for clarifying :)

// another path
function(h,b,c){b=.5*!!h[4];c=1;return['0x'+h[c+=b]+h[c+=b]|0,'0x'+h[c+=b]+h[c+=b]|0,'0x'+h[c+=b]+h[c+=b]|0]}

// kuvos's path
function(h,b){b=h[4];return['0x'+h[1]+h[b?2:1]|0,'0x'+h[b?3:2]+h[b?4:2]|0,'0x'+h[b?5:3]+h[b?6:3]|0]}
function(h,b){b=!!h[4];return['0x'+h[1]+h[b+1]|0,'0x'+h[b+2]+h[2*b+2]|0,'0x'+h[2*b+3]+h[3*b+3]|0]}
function(h,b){b=!!h[4];return['0x'+h[1]+h[b+1]|0,'0x'+h[b+2]+h[2*b+2]|0,'0x'+h[2*b+3]+h[3*b+3]|0]}
function(h,b){b=!!h[4]+1;return['0x'+h[1]+h[b]|0,'0x'+h[b+1]+h[2*b]|0,'0x'+h[2*b+1]+h[3*b]|0]}

// Asen's path
function(h){h='0x'+(h[4]?h:h.replace(/./g,'$&$&')).slice(1+!h[4])-0;return[h>>16,h>>8&255,h&255]}
function(h){h=h.slice(1);h[4]||(h=h.replace(/./g,'$&$&'));h='0x'+h-0;return[h>>16,h>>8&255,h&255]}
function(h,b){h='0x'+((b=h[4])?h:h.replace(/./g,'$&$&')).slice(1+!b)-0;return[h>>16,h>>8&255,h&255]}
// + jed's trick
function(h){h='0x'+h.replace(!h[4]&&/./g,'$&$&').slice(1+!h[4])-0;return[h>>16,h>>8&255,h&255]}

//var _fn = 
_log(_fn('#abc'))
_log(_fn('#123456'))

@bga Great stuff!

!foo && bar can be written as foo || bar, so you could rewrite that last one as follows to save a byte (95→94 bytes):

function(h){h='0x'+h.replace(h[4]||/./g,'$&$&').slice(1+!h[4])-0;return[h>>16,h>>8&255,h&255]}

Edit: Actually, no — that would break it, of course, since it’s used for .replace() so it needs to be false. Ignore me! :)

@mathiasbynens no.

'#bbaacc'.replace('a', '$&$&')

I've tested the code in IE6, 8, and it returns a wrong result as a string doesn't act like an array in those IE versions. I think a[4] should be replaced by a.length>4

fixed. thanks again, @tsaniel!

I find it we can save another byte.

function(a){a='0x'+a.slice(1).replace(a.length>4&&/./g,'$&$&');return[a>>16,a>>8&255,a&255]}

relentless golfing, @tsaniel!

Wait, >4? Doesn't it need to be the other way round, <4?

@atk: Thanks for your carefulness! i just did it anyhow.

Both wrong with >4 and <4
Shound be a.length<5&&/./g

function hexToRgb(hex) {
var number = parseInt(hex, 16);
console.log(number)
var r = (number >> 16) & 255;
var g = (number >> 8) & 255;
var b = number & 255;
console.log(r,g,b)
return {red: r, green: g, blue: b};
}
let rgb = hexToRgb(0xFFFFFF)
Gives 119 114 21 , any ideas why