README.md

react-stable-ref 🤷‍♂️

Your stable reference utility library with everything you need to test, visualize and protect against the dreaded unintentional rerender 😱

Try it here

Get started 🏗

Installation

npm install --save react-stable-ref or yarn add react-stable-ref

Example

const UnstableButton: FC<ButtonProps> = ({ onClick, children }) => {
    // Unstable reference (unstableArray is reassigned on every render)
    const unstableArray = ['1', '2', '3'];
    const stableValue = 'Im stable because im a string';

    useStableRefTester(); // Triggers re-renders every second
    useWhichDepChanged({ unstableArray, stableValue });
    /**
     * Will output the following to the console (or onChange if you pass it in)
     *
     * > [useWhichDepChanged]: { unstableArray: { from: [1, 2, 3]; to: [1, 2, 3]}}
     */

    return (
        <button type="button" onClick={onClick}>
            {children}
        </button>
    );
};

Motivation 🧠

It's not always obvious when unstable references are passed into hooks such as useEffect. This can cause unnecessary rerenders, which when left unchecked can decrease the performance of your app, cause jank and ultimately degrade your user's experience 😭.

Thankfully the React team have already thought about this and provided lint rules to help 🥰. But what if you're passing objects and arrays into dependency arrays which are not 'deeply' compared? How can you know for sure?

react-stable-ref fills that gap and provides an assortment of utilities to help test, visualize and protect against the dreaded re-render 😱.

API 🤖

useStableRefTester()

A development only hook, which increments state over a predefined interval, triggering rerenders in your component.

Arguments:

• timeout: Number Timeout between rerenders

Returns:

count: Number

Example:

const UnstableButton = ({ children }) => {
    const myArray = ['1', '2', '3'];

    useStableRefTester();

    useEffect(() => {
        console.warn('I should not be called on every render');
    }, [myArray]);

    return <button>{children}</button>;
};

useWhichDepChanged()

A development only hook which emits (via console) which prop triggered an update. Useful when you are unsure which property changed in a useEffect dependency array.

Inspired by: useWhyDidYouUpdate

Arguments:

• dependencies: Object A dependency object which mirrors the dependency array of the hook you are trying to test
• onChange(changedDeps): (changedDeps: Obj) => void A callback which is fired when a dependency is changed.

Returns:

void

Example:

const UnstableButton = ({ children }) => {
    const myArray = ['1', '2', '3'];

    useWhichDepChanged({ myArray, children }, onChange(changedDeps) => {
        console.log('UnstableButton: ', changedDeps); // UnstableButton: myArray
    });

    return <button>{children}</button>;
};

useRenderCount()

A hook which returns how many times it has been rendered.

Arguments:

• initialCount: Number Initial counter value

Returns:

• count: Number Current counter value

Example:

const RenderCounter = () => {
    const count = useRenderCount();

    return <button>{count}</button>;
};

<RenderCount />

A visual component that keeps track of the number of renders that have occurred.

Props:

• initialCount: Number Initial counter value
• count: Number Provide a count for a controlled API

useDeeplyComparedEffect()

Coming soon...

A react hook for deeply comparing objects and arrays passed into its dependency array.

useCustomComparedEffect()

Coming soon...

A react hook to allow you to provide custom methods used to comparing dependencies and trigger an effect.

Thanks 😍

Huge thank you to Pablo Stanley and contributors of Open Peeps for the logo.

Resources

• Introducing Hooks
• Making Sense of React Hooks
• When to useMemo and useCallback