New to expressions and formulas? Try Expressions: The Essentials.
You can also learn more about the types of expressions you can use in your app.
Within the app editor, Expression Assistant can be found anywhere you're able to enter a expression, noted by a flask icon next to the input field:
Clicking the flask will open Expression Assistant:
The green check mark (1) indicates that your expression's syntax is correct. Examples for all available functions are provided (2). Use the Test button (3) to see how your expression works.
The expression tester is used to quickly preview what the expression result is for each row.
In addition to the expression result, you can expand the expression to see what each step of the expression does.