no-tracked-built-ins.md

ember/no-tracked-built-ins

🔧 This rule is automatically fixable by the --fix CLI option.

Enforce usage of @ember/reactive/collections imports instead of tracked-built-ins.

Context

Per RFC #1068, the tracked collection utilities from the tracked-built-ins package are being moved into the framework as @ember/reactive/collections. The new API also changes from class constructors (new TrackedArray(...)) to factory functions (trackedArray(...)).

Rule Details

This rule detects imports from tracked-built-ins and provides an autofix to convert them to @ember/reactive/collections with the new function-based API.

The following mappings are applied:

Old (tracked-built-ins)	New (@ember/reactive/collections)
TrackedArray	trackedArray
TrackedObject	trackedObject
TrackedMap	trackedMap
TrackedSet	trackedSet
TrackedWeakMap	trackedWeakMap
TrackedWeakSet	trackedWeakSet

Additionally, new expressions using these imports are automatically converted to direct function calls.

Examples

Examples of incorrect code for this rule:

import { TrackedArray } from 'tracked-built-ins';

const arr = new TrackedArray([1, 2, 3]);

import { TrackedObject, TrackedMap } from 'tracked-built-ins';

const obj = new TrackedObject({ a: 1 });
const map = new TrackedMap();

Examples of correct code for this rule:

import { trackedArray } from '@ember/reactive/collections';

const arr = trackedArray([1, 2, 3]);

import { trackedObject, trackedMap } from '@ember/reactive/collections';

const obj = trackedObject({ a: 1 });
const map = trackedMap();

Migration

This rule provides automatic fixes via --fix. Running ESLint with the --fix flag will:

1. Replace import { TrackedArray } from 'tracked-built-ins' with import { trackedArray } from '@ember/reactive/collections'
2. Replace new TrackedArray(...) with trackedArray(...)

References

• RFC #1068: Built in tracking utilities for common collections
• tracked-built-ins package