netinlet

I have always been annoyed at having to write email addresses online such as foo _at_ bar dot com. Damn the spambots!

I recently ran across this technique for obfuscating email addresses on web pages so that it appears normal to the user, but not something which could be easily parsed by a spambot.

<a href="mailto:foo@bar.com">foo@bar.com</a>

<a href="&#109;&#97;&#105;&#108;&#116;&#111;&#58;&#102;&#111;&#111;&#64;&#98;&#97;
                 &#114;&#46;&#99;&#111;&#109;&#10;">
                 &#102;&#111;&#111;&#64;&#98;&#97;&#114;&#46;&#99;&#111;&#109;&#10;</a> 

Just a little bit more cryptic.

The core method for converting a string to an html character string is just a one line ruby method, of course.

def string_to_htmlc(s)
  s.strip.unpack("C*").map{|ch| "&#" + ch.to_s + ";" }.to_s
end

A couple of things are going on here.

We now need to convert our array of integers into the html code for each character. The html code for a character is simply the ascii integer value for that character preceded by &# and ending with a ;. The ruby map mehtod takes care of this for us. Array#map invokes the block for each element in the array.

Finally we convert the array back into a string with the .to_s for our html pleasure. The .to_s method on array is the same as calling array.join

All you have to do now is just put some code in your rails helper module to output a full href.

module MyHelper
  def to_html_email(address)
    email = string_to_htmlc(address)
    "<a href=\"#{string_to_htmlc('mailto:')}#{email}\">#{email}</a>" 
  end

  def string_to_htmlc(s)
    s.strip.unpack("C*").map{|ch| "&#" + ch.to_s + ";" }.to_s
  end
end

Now it should be safe to display an email address on a webpage. doug@netinlet.com