@shopify/react-hooks

@shopify/react-hooks

A collection of primitive React hooks.

Installation

$ yarn add @shopify/react-hooks

Usage

useOnValueChange()

This hook will track a given value and invoke a callback when it has changed.

function MyComponent({foo}: {foo: string}) {
  useOnValueChange(foo, (newValue, oldValue) => {
    console.log(`foo changed from ${oldValue} to ${newValue}`);
  });

  return null;
}

useTimeout()

This hook provides a declarative version of setTimeout(). The first argument is a callback that will be invoked after the given delay (number of milliseconds) as the second argument.

function MyComponent() {
  const [foo, setFoo] = React.useState('Bar');

  useTimeout(() => setFoo('Baz!'), 5000);

  return <div>{foo}</div>;
}

useLazyRef()

This hook creates a ref object like React’s useRef, but instead of providing it the value directly, you provide a function that returns the value. The first time the hook is run, it will call the function and use the returned value as the initial ref.current value. Afterwards, the function is never invoked. You can use this for creating refs to values that are expensive to initialize.

function MyComponent() {
  const ref = useLazyRef(() => someExpensiveOperation());

  React.useEffect(() => {
    console.log('Initialized expensive ref', ref.current);
  });

  return null;
}

useMountedRef()

This hook keep track of a component's mounted / un-mounted status and returns a ref object like React’s useRef with a boolean value representing said status. This is often use when a component contains async task that set state after the task resolved.

import React from 'react';
import {useMountedRef} from '@shopify/react-hooks';

function MockComponent() {
  const [result, setResult] = React.useState();
  const mounted = useMountedRef();

  async function handleOnClick() {
    const result = await fetchData();

    if (mounted.current) {
      setData(result);
    }
  }

  return (
    <button onClick={handleOnClick} type="button">
      Fetch Data
    </button>
  );
}

usePrevious()

This hook will store the previous value of a given variable.

function Score({value}) {
  const previousValue = usePrevious(value);
  const newRecord = value > previousValue ? <p>We have a new record!</p> : null;

  return (
    <>
      <p>Current score: {value}</p>
      {newRecord}
    </>
  );
}