10
3
This blog post about generating random CSS color codes in JavaScript have multiple solutions for generating a random color in JavaScript. The shortest I can find is this:
'#'+(Math.random()*0xffffff).toString(16).slice(-6)
If you are not familiar with CSS color code read documentations here.
Can we do better? What about other languages?
Mohsen
Posted 2013-09-16T21:14:06.277
Reputation: 677
26
#<?=md5(rand())&ÿÿÿÿÿÿ;
Where ÿ is character 255. Bitwise and will truncate the string returned from md5, which is already in hexadecimal format.
primo
Posted 2013-09-16T21:14:06.277
Reputation: 30 891
7This is one of my favourite solutions on the site. – Griffin – 2013-09-17T10:08:09.960
7
Three character codes are valid too, so I can save some chars (4095 == 0xfff):
'#%03x'%rand(4095)
If I have to use a 6-char one, then:
Shaved one character off because 8**8-1 == 0xffffff
'#%06x'%rand(8**8-1)
Thanks to chron for the format string, saving 4 chars!
Cheating (with this xkcd strip in mind):
"#a83"
I assure you, I generated it randomly!
An even cheatier version:
"red"
Doorknob
Posted 2013-09-16T21:14:06.277
Reputation: 68 138
You don't need parentheses for method calls in Ruby, right? – Mohsen – 2013-09-16T22:50:07.730
@Mohsen Yes, but Ruby gets confused and thinks I'm calling to_s on 4095 if I omit them. – Doorknob – 2013-09-16T22:51:08.523
You can get it down to 20 with a sprintf format string: '#%06x'%rand(8**8-1) – Paul Prestidge – 2013-09-17T00:04:41.837
@chron Nice, thanks! Editing – Doorknob – 2013-09-17T00:05:25.623
6
'#'+Math.random().toString(16).substr(2,6)
Just a little shorter at 42.
function randomColor() {
return '#' + Math.random().toString(16).substr(2, 6);
}
for (var n = 0; n < 16*9; n++) {
var el = document.createElement('SPAN');
el.style.backgroundColor = randomColor();
document.getElementById('demo').appendChild(el);
}span { width: calc(100%/16);
height: calc(100vh/9);
margin-top: -7px;
display: inline-block;
}<div id='demo'></div>
tristin
Posted 2013-09-16T21:14:06.277
Reputation: 189
1I'm not sure why this was downvoted. It works fine in every browser I've tested. +1 – primo – 2013-09-17T06:11:44.793
5#'+Math.random().toString(16).slice(-6) – Mohsen – 2013-09-17T22:30:40.383
@Mohsen nice! Didn't know slice could do negatives. – tristin – 2013-09-18T01:08:55.827
3
vnnnnnnnn
601234567;
>xxxxxxxx<
89""""""?
nnABCDEF:
vv""""""-
vvoooooo1
>>>>>>>>^
Not the shortest solution in the world, but it was fun to code :)
It's also not a uniform distribution, but all outputs have a non-zero probability 7 and F are most likely digits.
Outputs:
python fish.py randomColor.fish
07FFF7
python fish.py randomColor.fish
07EFD7
python fish.py randomColor.fish
366F67
python fish.py randomColor.fish
977FD7
python fish.py randomColor.fish
97F7F7
python fish.py randomColor.fish
87F6FF
Cruncher
Posted 2013-09-16T21:14:06.277
Reputation: 2 135
1
'#',(⎕D,⎕A)[6?16]
Explanation:
6?16: 6 random numbers from 1 to 16⎕D,⎕A: the digits (0..9) followed by the alphabet (A..Z) (but only the first 16 values are ever used, i.e. 0..F)'#',: add a # to the front
marinus
Posted 2013-09-16T21:14:06.277
Reputation: 30 224
6?16 is 6 non-repeating random values though, that narrows the colorspace a bit... – mniip – 2014-02-17T15:27:45.797
1
od -N4 -An -tx /dev/urandom | cut -c2-7 | sed s/^/#/
raspi
Posted 2013-09-16T21:14:06.277
Reputation: 121
0
Matthew Jensen
Posted 2013-09-16T21:14:06.277
Reputation: 713
Yours is broken, you're missing a
+after the'#'– Doorknob – 2013-09-16T22:29:35.6371You can remove the slice by doing this
#'+(Math.random()*0xffffff|0).toString(16)– Griffin – 2013-09-17T10:39:19.1831What is the "0xffffff" needed for? I'm not seeing much of a difference in my results without it. – path411 – 2013-09-17T22:18:21.007
4@path411 Theoretically,
Math.random().toString(16)can produce a representation with less than 6 hex-digits after the (hexa)decimal point, in which case the function would break. For example, 0.1658172607421875 becomes 0.2A73 in hex. – primo – 2013-09-18T08:51:11.067