SirTrevor h1, h2 and h3 formatters. The code isn't 100%, the regular expressions for toHTML methods are a little buggy, but I am working on it.

formatters.js.coffee

# Our base formatters

(->
  checkElementActive = () ->
    selection = window.getSelection()
    node = undefined
    node = selection.getRangeAt(0).startContainer.parentNode  if selection.rangeCount > 0
    node and node.nodeName is this.title.toUpperCase()

  formatBlockOnClick = () ->
    elem = if this.isActive() then '<div>' else this.param
    document.execCommand('formatBlock', false, elem)
    # http://stackoverflow.com/questions/10810940/javascript-document-execcommand-remove-formatblock-formatting

  H1 = SirTrevor.Formatter.extend(
    title: "h1"
    cmd: "formatBlock"
    keyCode: 49
    text: "h1"
    param: '<h1>'
    isActive: checkElementActive
    onClick: formatBlockOnClick
    toMarkdown: (content, type) ->
      content.replace(/<br>/,"\n").replace(/<h1.*?>(?:\s*)(.*?)(\s*)?<\/h1>/i, "#$1\n ")
    toHTML: (markdown, type) ->
      markdown.replace(/^\w*\s*\t*#\s*([^#]*)\s*$/, "<h1>$1</h1>\n")

  )
  H2 = SirTrevor.Formatter.extend(
    title: "h2"
    cmd: "formatBlock"
    keyCode: 451
    text: "h2"
    param: '<h2>'
    isActive: checkElementActive
    onClick: formatBlockOnClick
    toMarkdown: (content, type) ->
      content.replace(/<br\/?>/,"\n").replace(/<h2.*?>(?:\s*)(.*?)(\s*)?<\/h2>/i, "##$1\n ")
    toHTML: (markdown, type) ->
      markdown.replace(/^\w*\s*\t*##\s*([^#]*)\s*$/, "<h2>$1</h2>\n")
  )
  H3 = SirTrevor.Formatter.extend(
    title: "h3"
    cmd: "formatBlock"
    keyCode: 51
    text: "h3"
    param: '<h3>'
    isActive: checkElementActive
    onClick: formatBlockOnClick
    toMarkdown: (content, type) ->
      content.replace(/<br>/,"\n").replace(/<h3.*?>(?:\s*)(.*?)(\s*)?<\/h3>/i, "###$1\n ")
    toHTML: (markdown, type) ->
      markdown.replace(/^\w*\s*\t*###\s*([^#]*)\s*$/, "<h3>$1</h3>\n")

  )
  #
  #    Create our formatters and add a static reference to them
  #
  SirTrevor.Formatters.H1 = new H1()
  SirTrevor.Formatters.H2 = new H2()
  SirTrevor.Formatters.H3 = new H3()
)()