setInterval的停止与启动

var getting = {
                url:$scope.form.fileUrl,
                dataType:'text',
                success:function(res) {
                 if(res != ""){
                     clearInterval(interval);
                     var s = res.indexOf("<BODY");
                     var e = res.indexOf("</BODY>");
                     var re = res.substring(s,e);
                     re = re.replace("<BODY","<");
                     $scope.form.changeEditor(re,true);
                 }
              }
        }
        
        var interval = window.setInterval(function(){$.ajax(getting)},1000);