slugify.js

function slugify(str) {
  return str.toLowerCase().
             replace(/&/g, 'and').
             replace(/[^a-z0-9']+/g, '-').
             replace(/^-|-$/g, '');
}

slugify.rb

class String
  def slugify
    downcase.gsub(/&/, ' and ').gsub(/[^a-z0-9']+/, '-').gsub(/^-|-$|'/, '')
  end
end

slugify_spec.rb

require File.expand_path(File.dirname(__FILE__) + '/../spec_helper')

describe "String#slugify" do
  it "should slugify basic strings" do
    ''.slugify.should == ''
    'Hello'.slugify.should == 'hello'
    'ABC 123'.slugify.should == 'abc-123'
    'Save the chearleader'.slugify.should == 'save-the-chearleader'
  end
  
  it "should slugify strings with punctuation" do
    'Exclamation mark!'.slugify.should == 'exclamation-mark'
    'A comma, in a sentence'.slugify.should == 'a-comma-in-a-sentence'
    'The "end of the world"'.slugify.should == 'the-end-of-the-world'
    "Sam's page".slugify.should == 'sams-page'
  end
  
  it "should slugify hyphenated and underscored strings and strings with slashes" do
    'magic-missile'.slugify.should == 'magic-missile'
    'an_underscore'.slugify.should == 'an-underscore'
    'a/forward/slash'.slugify.should == 'a-forward-slash'
    'a\backward\slash'.slugify.should == 'a-backward-slash'
  end
  
  it "should remove consecutive hyphens from result" do
    'Title - subtitle'.slugify.should == 'title-subtitle'
    'Multiple    spaces'.slugify.should == 'multiple-spaces'
  end
  
  it "should remove hyphens at start and end of result" do
    ' hello '.slugify.should == 'hello'
  end

  it "should substitute & with and" do
    'American Dad & Family Guy'.slugify.should == 'american-dad-and-family-guy'
  end
end