Use DataSet when you want Set uniqueness with indexed read helpers and transformation methods. Use ReadonlySet when you want read-only access. Use set() when a callable i

Set

Extended Set utilities plus callable and readonly wrappers.

Import

import { DataSet, ReadonlySet, set } from '@stackpress/lib';

When To Use It

Use DataSet when you want Set uniqueness with indexed read helpers and transformation methods. Use ReadonlySet when you want read-only access. Use set() when a callable index-based getter is convenient.

API

Constructor

const tags = new DataSet<string>(['api', 'router', 'queue']);

ReadonlySet accepts the same initial array.

DataSet Methods

Method	Returns	Notes
`filter(callback)`	new `DataSet` subclass	Filters values by value and insertion index.
`find(callback)`	`[number, V] \	undefined`	First matching `[index, value]` .
`findIndex(callback)`	`number`	Returns `-1` when no value matches.
`findValue(callback)`	`V \	undefined`	First matching value.
`first()`	`V \	undefined`	Alias for `index(0)` .
`index(index)`	`V \	undefined`	Value by insertion order.
`last()`	`V \	undefined`	Value at `size - 1` .
`map(callback)`	new `DataSet<T>`	Maps each value into a new set.
`toArray()`	`V[]`	Array snapshot.
`toString(replacer?, space?)`	`string`	JSON string of `toArray()` .

ReadonlySet Methods

ReadonlySet exposes the read side of the collection:

entries()
filter(callback)
find(callback)
findIndex(callback)
findValue(callback)
forEach(iterator)
has(value)
index(index)
keys()
map(callback)
size
toArray()
toString(replacer?, space?)
values()

Callable Helper

const queue = set(['first', 'second']);

queue(0);
queue.index(1);
queue.add('third');

set(data?) returns a CallableSet<V> with the DataSet method surface plus a function signature for indexed reads.

Example

import { DataSet } from '@stackpress/lib';

const flags = new DataSet<number>();
flags.add(1);
flags.add(2);
flags.add(3);

const doubled = flags.map(value => value * 2);
const second = flags.index(1);
const found = flags.findValue(value => value === 3);

Set

Set