function checkEMail(campo){
	  var emailReg = "^[\\w\-_\.]*[\\w]\@[\\w\-\.]*[\\w]*$";
	  	var regex = new RegExp(emailReg);
	  	if (!regex.test(campo.value)) {
	   		alert("Debe introducir una dirección de correo válida");
			   
			   return false;
		  }else{
			   return true;
		  }
}

	function onlyLettersAndNumbers( string )
	{
		chars = string.toString();
		
		for ( var i = 0; i < chars.length; i++ )
		{
			var char = chars.charAt( i );
			
			if ( ( char < "0" ) ||
			     ( char > "9" && char < "A" ) ||
			     ( char > "Z" && char < "a" ) ||
			     ( char > "z" ) )
				return false;
		}
		
		return true;
	}
	
	function checkFloat( value )
	{
		if ( value == '' ) return false;
		
		rExp = /,/g;
		
		newValue = new String( value );
		
		value = newValue.replace( rExp, "." );
		
		if ( isNaN( value ) || ( isNaN( parseFloat( value ) ) ) )
		{
			return false;
		}
		
		return true;
	}

	function checkValidImageExtension( value )
	{
		var extension = value.substring( value.length - 3, value.length );
		
		extension = extension.toLowerCase();
		
		if ( extension == 'jpg' || extension == 'gif' || extension == 'png' )
		{
			return true;
		}
		else
		{
			alert( 'Sólo se admiten imagenes en formato GIF, JPG y PNG' );
			return false;
		}
	}
	
	function noCommas( control )
	{
		control.value = control.value.replace(/,/, '.');
	}