Script Blocks

HTML Mode supports restricted helper scripts for reusable survey logic. Script helpers are evaluated once into a safe helper surface and can then be used by if, <condition>, <run-code>, <validation>, and Template Expressions.

Helper declaration

<script name="LogicHelpers">
function isTarget(age, gender) {
  return age.value >= 18 && gender.o1;
}
 
registerSurveyHelper("segmentLabel", function(segment) {
  return String(segment || "direct").trim().toUpperCase();
});
</script>
 
<question type="single" name="FOLLOWUP" if="isTarget(AGE, GENDER)">
  <description>{{ segmentLabel($params.source) }} segment follow-up</description>
  <option value="1">Continue</option>
</question>

Both safe top-level function declarations and registerSurveyHelper(name, function (...) { ... }) are supported.

Helper inputs

Pass question objects or primitive values explicitly.

<question type="single" name="Q1">
  <run-code>
    if (segmentLabel($params.source) === "PARTNER" && $curr.o1) {
      setAnswer("PARTNER_SEGMENT", 1);
    }
  </run-code>
  <option value="1">Partner path</option>
</question>

A helper can read values passed to it, but it must not mutate answers directly. Use <run-code> with setAnswer, clearAnswer, or question-object mutation methods for mutation.

Runtime namespaces and helper inputs

Consuming DSL contexts run alongside the safe runtime helpers documented in Runtime & Logic and can pass those values into script helpers:

• Luxon.DateTime, Luxon.Duration, Luxon.Interval
• $now when the consuming runtime context provides it
• $params when Survey Link/runtime params are provided
• $curr only in question-local consuming contexts
• $status only in redirect route if evaluation

The helper body itself should read its function arguments rather than reaching for $params, $curr, or $status directly. Pass runtime values explicitly, for example segmentLabel($params.source) or isTarget($curr, $now.year).

Safety rules

• Save-time validation checks JavaScript-bearing DSL before persistence.
• Dangerous browser, server, network, storage, dynamic evaluation, timer, and prototype escape surfaces are blocked.
• Local functions, loops, object literals, arrays, and try or catch are allowed when they stay inside the safe runtime policy.
• Helper code should stay pure and deterministic. Prefer returning booleans, strings, numbers, or small objects.
• Do not add new global names that collide with reserved runtime names such as $curr, $now, $params, $status, Luxon, Math, or question names.

Run generate parity

Run generate uses the same helper context as Survey Link simulation. If a helper drives auto-punching or branch logic, include scenario overrides that exercise each branch and verify the generated response/export data.