List Operations on Sharepoint Apps: using ECMAScript

Below content will help to guide you on below things:

1. How to get the host web url? 
2. How to check whether the list exists or not? 
3. How to create a list? 
4. How to create fields? 
5. How to add Items into the list? 
6. How to Read items from the list?

Just replace the below code with your "app.js" file on office365(Napa tool) and see the magic.  Please give the required permission levels to do CRUD operations on the hosted site like read/write permissions otherwise get access denied error.

Access denied on: Napa tool/ SharePoint 2013 apps

Recently I got the "Access Denied" issue when I try to access the lists data from the Visual Studio 2012 apps and Napa tool.

To get the access permissions from the Napa tool:
You will get the below popup up window once you clicked on "properties" tab[see below fig] and here you can give the access according to your functionality.

List item count is zero in SharePoint apps:

If you are getting the count as zero even the data exists means that you don’t have item level permissions. Please follow up the below steps to give permissions at the list item levels in apps.

Another way to add permissions:

Just right click on “Appmanifest.xml”, select “view code” and then add the below code in it.