Accessible Surveys

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Jexl Syntax Reference ​

Accessible Surveys relies on the Jexl library to evaluate logic expressions safely and dynamically. This page provides a quick reference to Jexl's core syntax capabilities.

Native Types ​

Jexl supports standard data types:

  • Booleans: true, false
  • Strings: "Double quotes" or 'Single quotes'
  • Numerics: Integers and floats (e.g., 6, -7.2)
  • Objects: {key: "value"}
  • Arrays: ['element1', 'element2']

Operators ​

Unary Operators ​

  • Negate (!): Logical NOT (e.g., !true is false).

Binary Operators ​

  • Arithmetic: + (Addition/Concat), - (Subtraction), * (Multiplication), / (Division), // (Integer Division), % (Modulus), ^ (Power of).
  • Logical: && (AND), || (OR).

Comparisons ​

  • Standard: ==, !=, >, >=, <, <=.
  • Membership (in):
    • Checks for a substring: "Cad" in "Ron Cadillac" evaluates to true.
    • Checks for an array element: "coarse" in ['fine', 'medium', 'coarse'] evaluates to true.
    • Crucial for Group Questions: Since Checkbox Group questions store answers in an array, you must use in to verify if a specific option is selected.
    • Note: Uses == internally, so it won't match objects by value (e.g., {a: 'b'} in [{a: 'b'}] is false).

Ternary Operator ​

  • Standard: condition ? consequent : alternate (e.g., age > 62 ? "retired" : "working").
  • Elvis Operator (Short-hand): value ?: alternate (returns value if truthy, otherwise alternate).

Identifiers & Data Access ​

Jexl evaluates expressions against a context object (in this case, the respondent's answers).

  • Variables (Bound Fields): Access context variables by name. In Accessible Surveys, these variables represent the specific survey questions or options you have bound to the expression (typically by dragging and dropping them into the logic editor).
  • Dot Notation: Traverse objects (e.g., person.firstName).
  • Bracket Notation: Dynamic property access or array indexing (e.g., person["last" + "Name"], answers[1]).

Collections & Filtering ​

You can filter arrays of objects using brackets and a leading dot for properties.

  • Filtering: employees[.first == 'Sterling'] returns an array of matching objects.
  • Chaining: employees[.age > 30][.age < 40]

Transforms & Functions ​

  • Transforms (|): Pipe a value into a function.
    • Syntax: value|transformName or value|transformName(arg1, arg2).
    • Example: "hello"|upper.
  • Functions: Top-level functions.
    • Syntax: functionName(arg1, arg2).
    • Example: min(4, 2, 19).