Hooks contains our logic code in our React app.
We can create our own hooks and use hooks provided by other people.
In this article, we’ll look at some useful React hooks.
react-use
The react-use library is a big library with many handy hooks.
useStateValidator
We can use the useStateValidator
hook to validate the state that’s changed in our app.
For instance, we can write:
import React from "react";
import { useStateValidator } from "react-use";
const NumberValidator = s => [s === "" || (s * 1) % 2 === 0];
export default function App() {
const [state, setState] = React.useState(0);
const [[isValid]] = useStateValidator(state, NumberValidator);
return (
<div>
<input
type="number"
min="0"
max="10"
value={state}
onChange={ev => setState(ev.target.value)}
/>
<br />
{isValid !== null && <span>{isValid ? "Valid" : "Invalid"}</span>}
</div>
);
}
to use the useStateValidator
to validate the state.
We pass in the state
as the first argument.
The 2nd is the NumberValidator
to validate our state.
It takes the state and returns an array that has the validation state of the state
.
It returns an array that’s nested in an array with the validation state.
Then we can use that anywhere we like.
useStateHistory
The useStateHistory
hook lets us store a set amount of previous state values and provides handles to travel through them.
To use it, we can write:
import React from "react";
import { useStateWithHistory } from "react-use";
export default function App() {
const [state, setState, stateHistory] = useStateWithHistory(2, 10, [1]);
return (
<div>
<button onClick={() => setState(state + 1)}>increment</button>
<p>{JSON.stringify(stateHistory, null, 2)}</p>
<p>{JSON.stringify(state)}</p>
</div>
);
}
We use the useStateWithHistory
hook with a few arguments.
The first argument is the initial state.
The 2nd argument is the maximum number of items to keep.
The 3rd is the initial history.
It returns an array with the state
which has the state value.
setState
lets us update the state.
stateHistory
has the state history.
It’s an object with various methods.
The position
has the position in history.
capacity
has the max capacity of the history list.
back
lets us move backward in the state history.
forward
lets us move forward in the state history.
go
lets us go to an arbitrary position in the state history.
useMultiStateValidator
The useMultiStateValidator
hook lets us invoke a validator function if any state changes.
For instance, we can write:
import React from "react";
import { useMultiStateValidator } from "react-use";
const NumberValidator = s => [s.every(num => num % 2 === 0)];
export default function App() {
const [state1, setState1] = React.useState(1);
const [state2, setState2] = React.useState(1);
const [state3, setState3] = React.useState(1);
const [[isValid]] = useMultiStateValidator(
[state1, state2, state3],
NumberValidator
);
return (
<div>
<input
type="number"
min="1"
max="10"
value={state1}
onChange={ev => {
setState1(ev.target.value);
}}
/>
<input
type="number"
min="1"
max="10"
value={state2}
onChange={ev => {
setState2(ev.target.value);
}}
/>
<input
type="number"
min="1"
max="10"
value={state3}
onChange={ev => {
setState3(ev.target.value);
}}
/>
{isValid !== null && <span>{isValid ? "Valid" : "Invalid"}</span>}
</div>
);
}
We have 3 states, which we can set with their own input box.
And we call useMultiStateValidator
with the numbers and the NumberValidator
to validate the numbers.
NumberValidator
takes has an array with the array we passed in as the argument.
And it returns an array with the validation condition of all the entries.
It returns a nested array with the validation state of all the numbers.
It’ll only return true
if all of them meet the criteria in the callback for every
as we specified.
Conclusion
The react-use library lets us validate states and list the past values of a state in an array.