Why does HTML think “chucknorris” is a color?

I'm sorry to disagree, but according to the rules for parsing a legacy color value posted by @Yuhong Bao, chucknorris DOES NOT equate to #CC0000, but rather to #C00000, a very similar but slightly different hue of red. I used the Firefox ColorZilla add-on to verify this.

The rules state:

• make the string a length that is a multiple of 3 by adding 0s: chucknorris0
• separate the string into 3 equal length strings: chuc knor ris0
• truncate each string to 2 characters: ch kn ri
• keep the hex values, and add 0's where necessary: C0 00 00

I was able to use these rules to correctly interpret the following strings:

• LuckyCharms
• Luck
• LuckBeALady
• LuckBeALadyTonight
• GangnamStyle

Unfortunately I have not yet been able to determine why this doesn't seem to work for adamlevine which should be ADE0E0 but it's actually AD0E0E.

Edit:

adamlevine does work as per http://jsfiddle.net/LdyZ8/2959/ but the letters are blocked into ada00e000e which is padded to ada00e000e00 but then reduced down to the typical HEX 6 digit value of [ad]a0[0e]00[0e]00 thus making ad0e0e which appears in the jsfiddle above.

UPDATE: The original answerers who said the color was #CC0000 have since edited their answers to include the correction.

Most browsers will simply ignore any NON-hex values in your color string, substituting non-hex digits with zeros.

ChuCknorris translates to c00c0000000. At this point, the browser will divide the string into three equal sections, indicating Red, Green and Blue values: c00c 0000 0000. Extra bits in each section will be ignored, which makes the final result #c00000 which is a reddish color.

Note, this does not apply to CSS color parsing, which follow the CSS standard.

<p><font color='chucknorris'>Redish</font></p>
<p><font color='#c00000'>Same as above</font></p>
<p><span style="color: chucknorris">Black</span></p>

The WHATWG HTML spec has the exact algorithm for parsing a legacy color value: https://html.spec.whatwg.org/multipage/infrastructure.html#rules-for-parsing-a-legacy-colour-value

The code Netscape Classic used for parsing color strings is open source: https://dxr.mozilla.org/classic/source/lib/layout/layimage.c#155

For example, notice that each character is parsed as a hex digit and then is shifted into a 32-bit integer without checking for overflow. Only eight hex digits fit into a 32-bit integer, which is why only the last 8 characters are considered. After parsing the hex digits into 32-bit integers, they are then truncated into 8-bit integers by dividing them by 16 until they fit into 8-bit, which is why leading zeros are ignored.

Update: this code does not exactly match what is defined in the spec, but the only difference there is a few lines of code. I think it is these lines that was added (in Netscape 4):

if (bytes_per_val > 4)
{
      bytes_per_val = 4;
}

The browser is trying to convert chucknorris into hex colour code, because it's not a valid value.

1. In chucknorris, everything except c is not a valid hex value.
2. So it gets converted to c00c00000000.
3. Which becomes #c00000, a shade of red.

This seems to be an issue primarily with Internet Explorer and Opera (12) as both Chrome (31) and Firefox (26) just ignore this.

P.S. The numbers in brackets are the browser versions I tested on.

.

On a lighter note

Chuck Norris doesn't conform to web standards. Web standards conform to him. #BADA55

Answer:

• The browser will try to convert chucknorris into a hexadecimal value.
• Since c is the only valid hex character in chucknorris, the value turns into: c00c00000000(0 for all values that were invalid).
• The browser then divides the result into 3 groupds: Red = c00c, Green = 0000, Blue = 0000.
• Since valid hex values for html backgrounds only contain 2 digits for each color type (r, g, b), the last 2 digits are truncated from each group, leaving an rgb value of c00000 which is a brick-reddish toned color.

Legend has it:

• Chucknorris leaves blood-red backgrounds where ever he goes, including websites.

The reason is the browser can not understand it and try to somehow translate it to what it can understand, in this case into a hexadecimal value!

chucknorris starts with c which is recognised character in hexadecimal, also it's converting all unrecognised characters into 0!

So chucknorris in hexadecimal format becomes: c00c00000000, all other characters become 0 and c remains where they are...

Now they get divided by 3 for RGB(red, green, blue)... R: c00c, G: 0000, B:0000...

But we know valid hexadecimal for RGB is just 2 characters, means R: c0, G: 00, B:00

So the real result is:

bgcolor="#c00000";

I also did the steps in the image as a quick reference: