A question about cleanupEffect in reactivity/effect.ts

[SnowingFox]

when i read effect.ts, i found this function

function cleanupEffect(effect: ReactiveEffect) {
  const { deps } = effect
  if (deps.length) {
    for (let i = 0; i < deps.length; i++) {
      deps[i].delete(effect)
    }
    deps.length = 0
  }
}

I have a question, why should we clean deps?

for (let i = 0; i < deps.length; i++) {
    deps[i].delete(effect)
}

I found the deps type declaration is a similarly to Set[], so why not set the deps length to 0 which also can clear deps item like this

deps.length = 0

[jods4]

You need to clean both ways.

An effect has a deps: Dep[], which is a list of dependencies that can trigger the effect.
Each dependency is a Set<ReactiveEffect>, that contains all effects that are triggered when the dependency changes.

Note that dependencies can link to other (multiple) effects that also depend on it.

So when you want to disconnect all dependencies from an effect, you need two steps:

1. Remove the effect from each dependency:

for (let i = 0; i < deps.length; i++) {
    deps[i].delete(effect)
}

2. Remove every dependency from the effect:

deps.length = 0

[SnowingFox]

thanks, it's great for me to understand it😄