/**
     * Reference: Sandeep V. Tamhankar (stamhankar@hotmail.com),
     * http://javascript.internet.com
     */
    function emailValidator(emailStr) {
        if (emailStr.length == 0) {
            return false;
        }
        // TLD checking turned off by default
        var checkTLD=0;
        var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum)$/;
        var emailPat=/^(.+)@(.+)$/;
        var specialChars="\\(\\)><@,;:\\\\\\\"\\.\\[\\]";
        var validChars="\[^\\s" + specialChars + "\]";
        var quotedUser="(\"[^\"]*\")";
        var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;
        var atom=validChars + '+';
        var word="(" + atom + "|" + quotedUser + ")";
        var userPat=new RegExp("^" + word + "(\\." + word + ")*$");
        var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$");
        var matchArray=emailStr.match(emailPat);
        if (matchArray==null) {
            return false;
        }
        var user=matchArray[1];
        var domain=matchArray[2];
        for (i=0; i<user.length; i++) {
            if (user.charCodeAt(i)>127) {
                return false;
            }
        }
        for (i=0; i<domain.length; i++) {
            if (domain.charCodeAt(i)>127) {
                return false;
            }
        }
        if (user.match(userPat)==null) {
            return false;
        }
        var IPArray=domain.match(ipDomainPat);
        if (IPArray!=null) {
            for (var i=1;i<=4;i++) {
                if (IPArray[i]>255) {
                    return false;
                }
            }
            return true;
        }
        var atomPat=new RegExp("^" + atom + "$");
        var domArr=domain.split(".");
        var len=domArr.length;
        for (i=0;i<len;i++) {
            if (domArr[i].search(atomPat)==-1) {
                return false;
            }
        }
        if (checkTLD && domArr[domArr.length-1].length!=2 && 
            domArr[domArr.length-1].search(knownDomsPat)==-1) {
            return false;
        }
        if (len<2) {
            return false;
        }
        return true;
    }
    
    /**
    *  field made of numbers and words
    */
    function fieldFormatValidator(value){
    	var mask = /^[A-Za-z0-9]+$/;
    	return regExValidator(value,mask);
    }
    
  function userNameFormatValidator(value){
    	var mask = /^[A-Za-z0-9_]+$/;
    	return regExValidator(value,mask);
    }
    
     /**
    *  field made of numbers and words
    */
    function fieldBlankValidator(value){
    	if(0 == value.length)
    		return true;
    	else{
	    	var mask = /^[ \t]+$/;
	    	return regExValidator(value,mask);
    	}
    }
    
    /**
    * made by numbers
    */
    function regExValidator(value,mask) 
	{ 
      	if(!mask.exec(value))
      		return false;
      	else
      		return true;
	} 
	
	/**
	*  check field minlength
	*/
	function minLengthValidator(value,length){
		return ( value.length >= length);
	}
	
	/**
	*   check field maxlength
	*/
	function maxLengthValidator(value,length){
		return (value.length <= length);
	}