The following is a very short list of things that I recommend should be done in the script:

• Some might say you should do as much as you can in the database. Most of the heavy lifting should be done in the database, but I would encourage you to leverage the power of the Qlik Sense script. This renders the tool unique and popular among Qlik enthusiasts. 
• Any expression or variables used in your front-end application should be created and kept within your Qlik Sense environment. Call it a spreadsheet or a .qvs file; anything is good when maintaining variables and expressions. In Chapter 9, Advanced Expressions in Qlik Sense, we will tell you how this can improve performance.
• Anything that is within the Qlik Sense scope and isn't used by other systems, such as derive fields or tables from source data.