@form2js/core

@form2js/core is the path parsing engine behind the rest of the package family. Use it when you already have key/value entries, need to turn them into nested objects, or want to flatten nested data back into entry form.

Installation

npm install @form2js/core

Standalone/global build is not shipped for this package.

General Example

import { entriesToObject, objectToEntries } from "@form2js/core";

const data = entriesToObject([
  { key: "person.name.first", value: "Esme" },
  { key: "person.roles[]", value: "witch" },
]);

const flat = objectToEntries(data);

Types and Properties

Exported Surface

Export	Kind	What it does
createMergeContext	function	Creates merge state used while parsing indexed arrays.
setPathValue	function	Applies one path/value into an object tree.
entriesToObject	function	Main parser for iterable entries.
objectToEntries	function	Flattens nested object/array data into { key, value } entries.
processNameValues	function	Compatibility helper for { name, value } input.
Entry, EntryInput, EntryValue, NameValuePair, ObjectTree, ParseOptions, MergeContext, MergeOptions, SchemaValidator, ValidationOptions, InferSchemaOutput	types	Public type surface for parser inputs, options, and results.

export function createMergeContext(): MergeContext;

export function setPathValue(
  target: ObjectTree,
  path: string,
  value: EntryValue,
  options?: MergeOptions
): ObjectTree;

export function entriesToObject(entries: Iterable<EntryInput>, options?: ParseOptions): ObjectTree;
export function entriesToObject<TSchema extends SchemaValidator>(
  entries: Iterable<EntryInput>,
  options: ParseOptions & { schema: TSchema }
): InferSchemaOutput<TSchema>;

export function objectToEntries(value: unknown): Entry[];

export function processNameValues(
  nameValues: Iterable<NameValuePair>,
  skipEmpty?: boolean,
  delimiter?: string
): ObjectTree;

Options And Defaults

Option	Default	Where	Why this matters
delimiter	"."	entriesToObject, setPathValue, processNameValues	Controls how dot-like path chunks are split.
skipEmpty	true	entriesToObject, processNameValues	Drops "" and null values unless you opt out.
allowUnsafePathSegments	false	entriesToObject, setPathValue	Blocks prototype-pollution path segments unless you explicitly trust the source.
schema	unset	entriesToObject	Runs schema.parse(parsedObject) and returns schema output type.
context	fresh merge context	setPathValue	Keeps indexed array compaction stable across multiple writes.

Schema validation

Use schema when you want parsing and validation in the same step. The parser only requires a structural { parse(unknown) } contract, so this works with Zod and similar validators.

import { z } from "zod";
import { entriesToObject } from "@form2js/core";

const PersonSchema = z.object({
  person: z.object({
    age: z.coerce.number().int().min(0),
    email: z.string().email()
  })
});

const rawEntries = [
  { key: "person.age", value: "17" },
  { key: "person.email", value: "esk@example.com" }
];

const result = entriesToObject(rawEntries, { schema: PersonSchema });

skipEmpty: false

Opt out of the default empty-value filtering when blank strings are meaningful in your payload.

import { entriesToObject } from "@form2js/core";

const result = entriesToObject(
  [{ key: "person.nickname", value: "" }],
  { skipEmpty: false }
);

Behavior Notes

• Indexed array keys are compacted by encounter order, not preserved by numeric index.
• EntryInput accepts [key, value], { key, value }, and { name, value }.
• If schema is provided, parser output is passed to schema.parse() and schema errors are rethrown.
• objectToEntries emits bracket indexes for arrays such as emails[0] and only serializes own enumerable properties.