docs: comments on reactivity functions (fixes vuejs#4832) (vuejs#4836)

close vuejs#4832

packages/compiler-sfc/src/templateUtils.ts

@@ -30,7 +30,7 @@ export function parseUrl(url: string): UrlWithStringQuery {
 
 /**
  * vuejs/component-compiler-utils#22 Support uri fragment in transformed require
- * @param urlString an url as a string
+ * @param urlString - an url as a string
  */
 function parseUriParts(urlString: string): UrlWithStringQuery {
  // A TypeError is thrown if urlString is not a string

packages/reactivity/src/computed.ts

@@ -68,6 +68,39 @@ export class ComputedRefImpl<T> {
  }
 }
 
+/**
+ * Takes a getter function and returns a readonly reactive ref object for the
+ * returned value from the getter. It can also take an object with get and set
+ * functions to create a writable ref object.
+ *
+ * @example
+ * ```js
+ * // Creating a readonly computed ref:
+ * const count = ref(1)
+ * const plusOne = computed(() => count.value + 1)
+ *
+ * console.log(plusOne.value) // 2
+ * plusOne.value++ // error
+ * ```
+ *
+ * ```js
+ * // Creating a writable computed ref:
+ * const count = ref(1)
+ * const plusOne = computed({
+ * get: () => count.value + 1,
+ * set: (val) => {
+ * count.value = val - 1
+ * }
+ * })
+ *
+ * plusOne.value = 1
+ * console.log(count.value) // 0
+ * ```
+ *
+ * @param getter - Function that produces the next value.
+ * @param debugOptions - For debugging. See {@link https://vuejs.org/guide/extras/reactivity-in-depth.html#computed-debugging}.
+ * @see {@link https://vuejs.org/api/reactivity-core.html#computed}
+ */
 export function computed<T>(
  getter: ComputedGetter<T>,
  debugOptions?: DebuggerOptions

packages/reactivity/src/effect.ts

@@ -167,6 +167,16 @@ export interface ReactiveEffectRunner<T = any> {
  effect: ReactiveEffect
 }
 
+/**
+ * Registers the given function to track reactive updates.
+ *
+ * The given function will be run once immediately. Every time any reactive
+ * property that's accessed within it gets updated, the function will run again.
+ *
+ * @param fn - The function that will track reactive updates.
+ * @param options - Allows to control the effect's behaviour.
+ * @returns A runner that can be used to control the effect after creation.
+ */
 export function effect<T = any>(
  fn: () => T,
  options?: ReactiveEffectOptions
@@ -188,28 +198,52 @@ export function effect<T = any>(
  return runner
 }
 
+/**
+ * Stops the effect associated with the given runner.
+ *
+ * @param runner - Association with the effect to stop tracking.
+ */
 export function stop(runner: ReactiveEffectRunner) {
  runner.effect.stop()
 }
 
 export let shouldTrack = true
 const trackStack: boolean[] = []
 
+/**
+ * Temporarily pauses tracking.
+ */
 export function pauseTracking() {
  trackStack.push(shouldTrack)
  shouldTrack = false
 }
 
+/**
+ * Re-enables effect tracking (if it was paused).
+ */
 export function enableTracking() {
  trackStack.push(shouldTrack)
  shouldTrack = true
 }
 
+/**
+ * Resets the previous global effect tracking state.
+ */
 export function resetTracking() {
  const last = trackStack.pop()
  shouldTrack = last === undefined ? true : last
 }
 
+/**
+ * Tracks access to a reactive property.
+ *
+ * This will check which effect is running at the moment and record it as dep
+ * which records all effects that depend on the reactive property.
+ *
+ * @param target - Object holding the reactive property.
+ * @param type - Defines the type of access to the reactive property.
+ * @param key - Identifier of the reactive property to track.
+ */
 export function track(target: object, type: TrackOpTypes, key: unknown) {
  if (shouldTrack && activeEffect) {
  let depsMap = targetMap.get(target)
@@ -260,6 +294,14 @@ export function trackEffects(
  }
 }
 
+/**
+ * Finds all deps associated with the target (or a specific property) and
+ * triggers the effects stored within.
+ *
+ * @param target - The reactive object.
+ * @param type - Defines the type of the operation that needs to trigger effects.
+ * @param key - Can be used to target a specific reactive property in the target object.
+ */
 export function trigger(
  target: object,
  type: TriggerOpTypes,

packages/reactivity/src/effectScope.ts

@@ -107,6 +107,15 @@ export class EffectScope {
  }
 }
 
+/**
+ * Creates an effect scope object which can capture the reactive effects (i.e.
+ * computed and watchers) created within it so that these effects can be
+ * disposed together. For detailed use cases of this API, please consult its
+ * corresponding {@link https://github.com/vuejs/rfcs/blob/master/active-rfcs/0041-reactivity-effect-scope.md | RFC}.
+ *
+ * @param detached - Can be used to create a "detached" effect scope.
+ * @see {@link https://vuejs.org/api/reactivity-advanced.html#effectscope}
+ */
 export function effectScope(detached?: boolean) {
  return new EffectScope(detached)
 }
@@ -120,10 +129,22 @@ export function recordEffectScope(
  }
 }
 
+/**
+ * Returns the current active effect scope if there is one.
+ *
+ * @see {@link https://vuejs.org/api/reactivity-advanced.html#getcurrentscope}
+ */
 export function getCurrentScope() {
  return activeEffectScope
 }
 
+/**
+ * Registers a dispose callback on the current active effect scope. The
+ * callback will be invoked when the associated effect scope is stopped.
+ *
+ * @param fn - The callback function to attach to the scope's cleanup.
+ * @see {@link https://vuejs.org/api/reactivity-advanced.html#onscopedispose}
+ */
 export function onScopeDispose(fn: () => void) {
  if (activeEffectScope) {
  activeEffectScope.cleanups.push(fn)