XFA Live Child Collections

JavaScript and FormCalc events can inspect the current child nodes of a form node or property node through its read-only nodes property

const field = xfa.resolveNode("row[1].amount");
const children = field.font.nodes;
const snapshot = children.clone();
field.font.fill.color.value = "192,48,96";
const fill = children.item(0);

Reading current children

The collection resolves its owner through the current event graph on each read, including a collection retained by a script object across events

Existing collections reflect repeated-instance additions and removals and implicit property creation; separate repeated instances keep separate property children and values

A retained collection whose owner was removed raises an error instead of targeting a surviving or replacement instance

FormCalc access

FormCalc recognises nodes as a child-collection property on form, property and Data DOM nodes

if (xfa.record.nodes.length >= 2) then
  xfa.record.nodes.item(1).nodes.namedItem("amount").rawValue = "Updated"
endif

Direct length, item(index), namedItem(name) and clone() member chains use the same current native nodes and collection limits as JavaScript

Form, property and Data DOM child collections support direct nodes[index] reads in both JavaScript and FormCalc

Collection indices are zero-based; for...of remains JavaScript syntax

Writes through a FormCalc collection reference update the actual bound data value and retain repeated-instance isolation; committed values survive XDP saving, runtime reloading and native PDF appearance generation

Data DOM numeric indices

const rows = xfa.record.nodes;
rows[1].nodes[0].rawValue = "Updated";

Canonical non-negative integer keys such as "0" and "1" resolve the current Data DOM child and return null outside the collection; noncanonical keys such as "01", "-0" and "1.0" do not alias numeric entries

JavaScript index in nodes checks the current child count, and direct assignment, deletion or redefinition of a canonical numeric entry raises TypeError

The same numeric-entry restrictions apply inside a script object function that retains the collection in lexical state, as well as when another event reads a collection returned by that function

Use the existing Data DOM structural methods to reorder or remove children; a collection retained by a script object reads the current event graph after each committed edit and after rollback

Independent clones

A cloned child list uses the independent storage described in XFA Query Node Collections; its append, insert and remove methods change that independent storage

Writing a node referenced by either list changes the actual native node, and committed values and property overrides persist through saved XDP and native PDF appearance generation

Data DOM child collections also provide clone() with independent entry storage; their existing structural append, insert and remove methods continue to mutate the native data tree

Transactions and limits

Live collection objects and independent clones share the event collection allocation limits, operation checks and transaction deadline

An uncaught event error or budget failure restores native values, repeated instances, retained script state, independent list storage and journal state together

Form and property live collections are read-only; direct assignment, deletion, property redefinition, prototype changes and preventing extensions raise an error

Data DOM collections reject writes, deletion and redefinition of canonical numeric entries whilst retaining their existing named structural methods and ordinary nonnumeric property behaviour

Coverage

This interface exposes current form and property child collections and independent child-list clones

General template/form node creation, recursive node cloning, child-tree insertion and removal, and additional node-class bindings remain separate work

Transactional XFA Data DOM Structure · XFA widget runtime