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Likftclist identity

Frames and identities

A frame is one complete ordered list. reconcile() compares it with the last committed frame and returns immutable entries, lifecycle events, and the next state.

import { createIdentityState, reconcile } from "@vp-tw/likftc";

const state = createIdentityState<string>();
const result = reconcile(state, items, { getId: (item) => item.id });

Rules

Section titled “Rules”
  • IDs are finite numbers or strings. 0, -0, and the empty string are valid.
  • Duplicate IDs reject the frame atomically. 0 and -0 are duplicates under JavaScript’s SameValueZero semantics.
  • Keys are monotonic numbers scoped to one adapter instance.
  • Core state stores only active IDs and keys. It does not retain item objects after they leave.
  • Exit events are emitted before events for the next active frame, making logs deterministic.

Re-entry is not retention

Section titled “Re-entry is not retention”

If a appears in frame 1, is absent in frame 2, and appears in frame 3, frame 3 is a new visual presence. Reusing the original key would let an exiting DOM node and an entering DOM node collide.