How to check for duplicate values before insert in visualforce remote objects?

How can i check for duplicate values while inserting data in salesforce using Visualforce Remote Objects. Here is my code:

 //Get form values.
     var woDetails = {
        Case__c: $scope.caseId,
        Name: $scope.Name,
        Priority__c: $scope.setPriority.priorityText,
        Status__c: $scope.Status,
        Description__c: $scope.Description,
        City__c: $scope.City,
        Street__c: $scope.Street,
        Zip__c: $scope.ZipCode
 };

  //Create work order
  var createWO = new WorkOrderModels.wo();
  //Insert work order details in work order object.
  createWO.create(woDetails, function(err) {
  if (err) {
    //Error message.
    msgBoxObj.showMessage(new messageBox().messageType.Error, err.message);
  } else {

    //Success message of Insert.
    msgBoxObj.showMessage(new messageBox().messageType.Success, "Work Order Saved Successfully!!");
    //Redirection.
     $window.location.href = "https://" + $window.location.host +"/apex/WorkOrderVF?" + "RecordId=" + $scope.caseId + "#/getWorkOrder";
     }
  });