18. Create selectors
In this section we will create selectors in NgRx which are a cornerstone piece of getting your NgRx architecture right.
Last updated
In this section we will create selectors in NgRx which are a cornerstone piece of getting your NgRx architecture right.
Last updated
Selectors are methods used for obtaining slices of store state. @ngrx/store provides a few helper functions for optimising this selection. Selectors are a big deal to help get your architecture right and you can read more in the docs here .
When using the createSelector
and createFeatureSelector
functions @ngrx/store keeps track of the latest arguments in which your selector function was invoked. Because selectors are , the last result can be returned when the arguments match without re-invoking your selector function. This can provide performance benefits, particularly with selectors that perform expensive computation. This practice is known as .
Make a spinner.selectors.ts file.
Make a getSpinnerState
using createFeatureSelector
, we can do this for other different feature state making it possible to join state slices together.
Make a getSpinner
selector using the createSelector
method to return just the boolean value of the isOn
property.
It is possible to see in this step how selectors clean our u=our code and make it easier for other developer son our team to know what they can get from the store.
Use the getSpinner selector versus our inline function where we "dot" into the property on the state tree we want.