this.method, finally safe to pass

React's Hooks announcement named the enemy honestly: classes "confuse both people and machines," and the star witness was this. Pass this.handleClick to a button and this is undefined at runtime. So a generation learned the rituals: .bind(this) in constructors (one allocated function per method per instance — there goes your prototype), arrow-function class fields (same cost, plus you lose overriding), or the () => this.method() wrapper at every call site, waiting for the one place someone forgets.

The entire bug class comes from one fact: JavaScript methods don't carry their object. Every workaround pays per-instance memory to compensate.

ivue's answer costs nothing until used and nothing extra after: methods stay on the prototype, and on first access the engine binds and caches the bound function on the instance. From then on:

const counter = new Counter()

const { increment } = counter   // detached — still correct
increment()                     // works: this === counter

counter.increment === counter.increment // true — stable identity, forever

Correct this, referential stability (event listeners unsubscribe cleanly, v-on handlers never re-bind, memoized children don't re-render), and you pay one bind per method you actually use. The live counter on the homepage hero runs exactly this — and here, with the buttons wired straight to dotted methods, no wrappers anywhere:

Your first class, runningLive · runs the shipped engine

count

0

double · plain getter

0

double is a plain getter, not a computed(). It re-derives whenever the component renders.

One honest footnote from our own benchmarks: a bound function call measures ~4 ns against ~1.4 ns for a raw closure — and if a hot loop ever cares, hoisting the method (const grow = instance.grow) reaches closure speed, because identity stability is what makes hoisting safe (Hot loops).

The wrapper era produced millions of arrow functions that exist only to say "yes, really, that object." Let them go: Reactive State — Methods.