77 lines
2.9 KiB
Markdown
77 lines
2.9 KiB
Markdown
# alien-signals
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Project Status: **Preview**
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The goal of `alien-signals` is to create a Signal library with the lowest overhead.
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We have set the following scheduling logic constraints:
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1. Based on Push-Pull
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2. No dynamic objects
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3. No use of Array/Set/Map
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4. No recursion calls
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5. Class properties must be fewer than 10 (https://v8.dev/blog/fast-properties)
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Experimental results have shown that with these constraints, it is possible to achieve excellent performance for a Signal library without using sophisticated scheduling strategies. The overall performance of `alien-signals` is approximately 400% that of Vue 3.4's reactivity system.
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For more detailed performance comparisons, please visit: https://github.com/transitive-bullshit/js-reactivity-benchmark
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## Motivation
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To achieve high-performance code generation in https://github.com/vuejs/language-tools, I needed to write some on-demand computed logic using Signals, but I couldn't find a low-cost Signal library that satisfied me.
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In the past, I accumulated some knowledge of reactivity systems in https://github.com/vuejs/core/pull/5912, so I attempted to develop `alien-signals` with the goal of creating a Signal library with minimal memory usage and excellent performance.
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Since Vue 3.5 switched to a Pull reactivity system in https://github.com/vuejs/core/pull/10397, I continued to research the Push-Pull reactivity system here. It is worth mentioning that I was inspired by the doubly-linked concept, but `alien-signals` does not use a similar implementation.
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## Usage
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### Basic
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```ts
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import { signal, computed, effect } from 'alien-signals';
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const count = signal(1);
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const doubleCount = computed(() => count.get() * 2);
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effect(() => {
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console.log(`Count is: ${count.get()}`);
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}); // Console: Count is: 1
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console.log(doubleCount.get()); // 2
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count.set(2); // Console: Count is: 2
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console.log(doubleCount.get()); // 4
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```
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### Effect Scope
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```ts
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import { signal, effectScope } from 'alien-signals';
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const count = signal(1);
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const scope = effectScope();
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scope.run(() => {
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effect(() => {
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console.log(`Count in scope: ${count.get()}`);
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}); // Console: Count in scope: 1
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count.set(2); // Console: Count in scope: 2
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});
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scope.stop();
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count.set(3); // No console output
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```
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## Roadmap
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| Version | Savings |
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|---------|-----------------------------------------------------------------------------------------------|
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| 0.3 | Correctly schedule child effect scopes |
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| 0.2 | Correctly schedule computed side effects |
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| 0.1 | Correctly schedule inner effect callbacks |
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| 0.0 | Add APIs: `signal()`, `computed()`, `effect()`, `effectScope()`, `startBatch()`, `endBatch()` |
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