function valider_champ()
{
  /* Validation mail */
  if( !emailCheck(document.erreur_identification.rappel_email_1.value) )
    {
      return false; 
    }
  else if( !emailCheck(document.erreur_identification.rappel_email_2.value) )
    {
      return false;
    }

    /* Validation prénom */
  else if (document.erreur_identification.rappel_prenom.value == 'Votre prénom ici' || document.erreur_identification.rappel_prenom.value.length < '3' || document.erreur_identification.rappel_prenom.value.length > '30')
    {
      alert ('Veuillez entrer votre prénom (entre 3 et 30 caractères)');
      return false;
    }

  /* Validation commentaires */
  /*
    else if (document.erreur_identification.rappel_commentaire.value == 'Vos commentaires ici' || document.erreur_identification.rappel_commentaire.value == 'Votre avis ici' || document.erreur_identification.rappel_commentaire.value.length < '10' || document.erreur_identification.rappel_commentaire.value.length > '1500')
    {
    alert ('Le commentaire est obligatoire et doit comporter entre 10 et 1500 caractères');
    return false;
    }
  */

    /* validation si tout est ok */
  else
    {
      return true;
    }
}
  
  /* 1.1.2: Fixed a bug where trailing . in e-mail address was passing
  (the bug is actually in the weak regexp engine of the browser; I
  simplified the regexps to make it work).
  1.1.1: Removed restriction that countries must be preceded by a domain,
  so abc@host.uk is now legal.  However, there's still the
  restriction that an address must end in a two or three letter
  word.
  1.1: Rewrote most of the function to conform more closely to RFC 822.
  1.0: Original  */
  
  <!-- This script and many more are available free online at -->
  <!-- The JavaScript Source!! http://javascript.internet.com -->
  
  <!-- Begin
  function emailCheck (emailStr) {
    /* The following pattern is used to check if the entered e-mail address
    fits the user@domain format.  It also is used to separate the username
    from the domain. */
    var emailPat=/^(.+)@(.+)$/

    /* The following string represents the pattern for matching all special
    characters.  We don't want to allow special characters in the address.
    These characters include ( ) < > @ , ; : \ " . [ ]    */
    var specialChars="\\(\\)<>@,;:\\\\\\\"\\.\\[\\]"

    /* The following string represents the range of characters allowed in a
    username or domainname.  It really states which chars aren't allowed. */
    var validChars="\[^\\s" + specialChars + "\]"

    /* The following pattern applies if the "user" is a quoted string (in
    which case, there are no rules about which characters are allowed
    and which aren't; anything goes).  E.g. "jiminy cricket"@disney.com
    is a legal e-mail address. */
    var quotedUser="(\"[^\"]*\")"

    /* The following pattern applies for domains that are IP addresses,
    rather than symbolic names.  E.g. joe@[123.124.233.4] is a legal
    e-mail address. NOTE: The square brackets are required. */
    var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/

    /* The following string represents an atom (basically a series of
    non-special characters.) */
    var atom=validChars + '+'

    /* The following string represents one word in the typical username.
    For example, in john.doe@somewhere.com, john and doe are words.
    Basically, a word is either an atom or quoted string. */
    var word="(" + atom + "|" + quotedUser + ")"

    // The following pattern describes the structure of the user
    var userPat=new RegExp("^" + word + "(\\." + word + ")*$")

    /* The following pattern describes the structure of a normal symbolic
    domain, as opposed to ipDomainPat, shown above. */
    var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$")
    
    /* Finally, let's start trying to figure out if the supplied address is
    valid. */
    
    /* Begin with the coarse pattern to simply break up user@domain into
    different pieces that are easy to analyze. */
    var matchArray=emailStr.match(emailPat)
    if (matchArray==null) {
      /* Too many/few @'s or something; basically, this address doesn't
      even fit the general mould of a valid e-mail address. */
      alert("L'adresse email semble incorrecte (veuillez vérifier les @ et les .)")
      return false
    }
    var user=matchArray[1]
    var domain=matchArray[2]
    
    // See if "user" is valid
    if (user.match(userPat)==null) {
      // user is not valid
      alert("Le nom d'utilisateur de messagerie semble incorrect.")
      return false
    }
    
    /* if the e-mail address is at an IP address (as opposed to a symbolic
    host name) make sure the IP address is valid. */
    var IPArray=domain.match(ipDomainPat)
    if (IPArray!=null) {
      // this is an IP address
      for (var i=1;i<=4;i++) {
        if (IPArray[i]>255) {
          alert("L'adresse IP pour de l'adresse email est invalide!")
          return false
        }
      }
      return true
    }
    // Domain is symbolic name
    var domainArray=domain.match(domainPat)
    if (domainArray==null) {
      alert("Le nom de domaine pour l'adresse email est invalide.")
      return false
    }
    
    /* domain name seems valid, but now make sure that it ends in a
    three-letter word (like com, edu, gov) or a two-letter word,
    representing country (uk, nl), and that there's a hostname preceding
    the domain or country. */
    
    /* Now we need to break up the domain to get a count of how many atoms
    it consists of. */
    var atomPat=new RegExp(atom,"g")
    var domArr=domain.match(atomPat)
    var len=domArr.length
    if (domArr[domArr.length-1].length<2 ||
      domArr[domArr.length-1].length>3) {
      // the address must end in a two letter or three letter word.
      alert("L'adresse email doit se terminer par un nom de domaine en 3 lettres ou un nom de pays en deux lettres.")
      return false
    }
    
    // Make sure there's a host name preceding the domain.
    if (len<2) {
      var errStr="L'adresse email n'a pas de nom de domaine!"
      alert(errStr)
      return false
    }
    
    // If we've gotten this far, everything's valid!
    return true;
  }
  //  End -->