granular-hooks
v1.1.0
Published
The React hooks you know, with added granularity
Downloads
18,031
Maintainers
Readme
granular-hooks
The React hooks you know, with added granularity. You can read more about this on Medium.
The problem
Who hasn't been in the situation where s/he needs an effect to run only when some of its dependencies have changed? Take this code for instance:
import { useEffect } from "react";
useEffect(() => {
if (condition) console.log("condition is true! value is", value);
else console.log("condition is false! value is", value);
}, [value, condition]);
Here, the effect prints to the console each time value
or condition
change. You cannot print to the console ONLY when value
changes because useEffect
wants that all values used by the effect are passed in the array of dependencies.
The solution
With minimal effort, useGranularEffect
allows you to splits the array of dependencies into two: primary dependencies and secondaries dependencies.
useGranularEffect
guarantees that:
- the effect only runs when the primary dependencies change
- the cleanup function (if any) only runs when the primary dependencies change
- when the effect runs, both primary and secondary dependencies are up-to-date
The example above can now be changed to:
import { useGranularEffect } from "granular-hooks";
useGranularEffect(
() => {
if (condition) console.log("condition is true! value is", value);
else console.log("condition is false! value is", value);
},
[value],
[condition]
);
Now the code only prints to the console when value
changes.
Installation
npm install granular-hooks
or
yarn add granular-hooks
Usage
import { useGranularEffect } from "granular-hooks";
useGranularEffect(
() => {
// the effect function, use your dependencies here
// dep1, dep2, dep3, dep4,...
// (optional) return a cleanup function
return () => {
/* cleanup*/
};
},
[dep1, dep2], // primary dependencies (runs when they change)
[dep3, dep4] // secondary dependencies (does not run when they change)
);
The only difference with useEffect
is that the array of dependencies is split into two (the primary dependencies and the secondary dependencies). In fact, useGranularEffect
uses useEffect
under the hood, thus the similarities.
See the React documentation for useEffect
for more information regarding the effect function, the optional cleanup function and dependencies.
Also check the general rules of hooks.
Other hooks
granular-hooks
also supports the following hooks:
useGranularLayoutEffect
, based on useLayoutEffectuseGranularMemo
, based on useMemouseGranularCallback
, based on useCallback
The hooks have the same signature as their React equivalents, except that the array of dependencies is split into two, just like with useGranularEffect
.
What's next?
Below are the features we're working on:
- [x] Why stop with granular effect? granular memos and callback are calling too! Stay tuned.
- [ ] What if we could also use a custom dependency comparer (other than the default
Object.is
)? - [ ] React hooks have a great ESLint plugin that makes sure you don't forget to list dependencies when calling them.
granular-hooks
are still missing such tools.
FAQ
Can I leave the primary array of dependencies empty?
You can. That means that the effect will only run once, when the component is mounted (the initial render).
Can I leave the secondary array of dependencies empty?
You could but that would defeat the purpose of the hook. You might as well call useEffect
directly.
Why use useGranularEffect
when I can just omit some dependencies in useEffect
?
While you could technically do so, it would violate the rules exposed in conditionally firing an effect:
make sure the array includes all values from the component scope (such as props and state) that change over time and that are used by the effect. Otherwise, your code will reference stale values from previous renders.
Having said that, it should still work as intended (see Understanding dependencies in useEffect). useGranularEffect
will however help you be explicit about your dependencies and it will make sure that the effect is called with an exhaustive list of dependencies, even though this is not stricly necessary technically speaking.