Always perform a null check before the element is being used in further logic.
Always follow the naming convention, as it makes the code easy to understand by any other programmer.
To make the code easily understandable, it is always preferred to write comments for JS methods with clear logic behind what a function does.
Use Sencha Touch recommended folder structure, which will be helpful during JS compression or minification.
It is highly recommended to use the listener (onclick/onblur, etc.) in the controller instead of writing it in the html page itself.
Do not create the store instance, when the store is being called from the view.
When we create an instance of a store, we should always destroy it, as it impacts the performance.
When the model mapping and the name are same, then do not specify mapping. Only name will solve the purpose.
Do not use unnecessary properties in view. Use only the property which is required and it value which is different from the default value.