- Contrast watchEffect
- 1. Lazy execution side effects, i.e. not executing the first time and waiting until the dependency changes
- 2. Show more clearly which state changes caused the side effects to be executed
- 3. You can access state to change the values before and after
- 4. WatchEffect automatically collects dependent values, whereas Watch needs to manually specify the side effects itself in the second returned function
- When the dependent value is a ref, the first argument can be written as a ref variable. Reactive doesn’t work.
Watch with multiple values monitors multiple values at the same time
+ also accepts a third parameter
- It also returns a stop function
