Sencha Touch - Best Practice

Basic JavaScript best practice:

It is good practice to keep all the JavaScript related code in a separate .js( external JS) file instead of writing it in the <script> tag under head section or inline JavaScript in document body.
Always do a null check before the element is getting used in the further logic.

Always follow the naming Convention as it makes the code easy to understand by any other programmer.
Writing comments for the JS methods with logic explained of what this function does makes the code easily understandable.

Best practice specific to Sencha Touch:

Use Sencha Touch recommended folder structure, which will be helping during JS compression or minification.
It is highly recommended to use listener (onclick/onblur etc) in controller instead of writing it in html page itself.
We should not create the store instance when store is being called from view.
When we create an instance of a store, we should always destroy it as it impacts the performance.
While using Sencha Touch do not specify any other simple JavaScript file use all the functions from Ext classes( mentioned in controller or utils).
When in model mapping and name are same then do not specify mapping only name will solve the purpose.
Do not use unnecessary properties in view only use the property which are required and their value is different from their default value.