Plug React
React components and hooks to plug your React applications into Croct.
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The React Plug library provides components and hooks for personalizing applications in real-time that are easy for your marketing team to scale and maintain.
- Easy integration: personalize existing components without touching their code.
- Suspense-ready: take advantage of the latest React features to improve user experience.
- Server-side rendering: seamless integration with server-side frameworks like Next.js.
- Zero configuration: no setup steps are required.
- Type-safety: Typescript typings are included for improved development experience.
- Blazing-fast queries: double-digit millisecond latency for real-time evaluations.
- Playground integration: one-click to connect, no configuration needed.
Check out the Storybook to see some minimal examples in action, or the example folder for full code examples.
The following steps will walk you through installing the library and integrating it into your application.
This guide assumes you're already familiar with some key concepts and tools around Croct, like Contextual Query Language (CQL) and the playground. If you're not, this 15-minute quickstart that will give you a hands-on overview of all the terms and tools you need to get started.
The recommended way to install the library is via NPM.
Run the following command to add the client as a dependency to your project and then install it:
npm install @croct/plug-react
You connect Croct to React with the <CroctProvider/ >
component. The <CroctProvider/ >
uses a regular React's
<Context.Provider />
to wrap your React app and make the SDK available anywhere in your component tree.
We suggest putting the <CroctProvider/ >
somewhere high in your app, above any component that might be personalized,
ideally in the top-level <App/>
component.
import {render} from 'react-dom';
import {CroctProvider} from '@croct/plug-react';
function App() {
return (
<CroctProvider appId="00000000-0000-0000-0000-000000000000">
<div>
<h1>My first personalized app ๐</h1>
</div>
</CroctProvider>
);
}
render(<App />, document.getElementById('root'));
Once your application is plugged in, you're ready to start personalizing your components using the <Personalization />
component or the useEvaluation
hook.
We'll go through a simple example that shows how you can implement feature flags (also known as feature toggles) to conditionally renders a different button depending on the user's persona.
Let's first implement the use-case using the <Personalization/>
component. It takes an expression (e.g. user's persona
)
and a render function, which tells the component how to render the UI, depending on the evaluation result.
This is what our component would look like:
import {ReactElement, Suspense} from 'react';
import {Personalization} from '@croct/plug-react';
function OnboardingPage(): ReactElement {
return (
<Suspense fallback="โจ Personalizing...">
<Personalization expression="user's persona is not 'developer'">
{(isDeveloper: boolean) => isDeveloper
? <a href="/docs">View docs</a>
: <a href="/share">Share with your developer</a>
}
</Personalization>
</Suspense>
)
}
If you don't want your component to suspend while loading, you can provide an initial
state to be rendered instead:
import {ReactElement} from 'react';
import {Personalization} from '@croct/plug-react';
function OnboardingPage(): ReactElement {
return (
<Personalization expression="user's persona is not 'developer'" initial={false}>
{(isDeveloper: boolean) => isDeveloper
? <a href="/docs">View docs</a>
: <a href="/share">Share with your developer</a>
}
</Personalization>
)
}
Now, let's create a ViewDocsLink
component to see the useEvaluation
hook in action:
import {ReactElement, Suspense} from 'react';
import {useEvaluation} from '@croct/plug-react';
function ViewDocsLink(): ReactElement {
const isDeveloper = useEvaluation<boolean>("user's persona is 'developer'");
return (
isDeveloper
? <a href="/docs">View docs</a>
: <a href="/share">Share with your developer</a>
);
}
export default function OnboardingPage(): ReactElement {
return (
<Suspense fallback="โจ Personalizing...">
<ViewDocsLink />
</Suspense>
)
}
If you run the application and there is no persona assigned to your profile, you will see the button for non-developers โ otherwise, the button for sharing the code with developers. Check out Accessing the Plug instance for an example of how to save information in a user's profile.
We strongly recommend always specifying the fallback
property to ensure your app behaves the same way regardless of
the personalization. In this way, the UI will still be fully functional even in maintenance windows.
The following example shows how you can specify a fallback behaviour for the docs link:
import {ReactElement, Fragment, Suspense} from 'react';
import {Personalization, useEvaluation} from '@croct/plug-react';
function ViewDocsLink(): ReactElement {
const isDeveloper = useEvaluation<boolean>("user's persona is 'developer'", {fallback: false});
return <Fragment>{isDeveloper && <a href="/docs">View docs</a>}</Fragment>
}
export default function OnboardingPage(): ReactElement {
return (
<Suspense fallback="โจ Personalizing...">
{/* Using the <Personalization /> component */}
<Personalization expression="user's persona is 'developer'" falback={false}>
{(isDeveloper: boolean) => (
<Fragment>
{isDeveloper && <a href="/docs">View docs</a>}
</Fragment>
)}
</Personalization>
{/* Using useEvaluation hook */}
<ViewDocsLink />
</Suspense>
)
}
For a full list of the available options, please refer to the API documentation.
Evaluating expression is a flexible and powerful way to customize your UI. However, for components whose content changes too often, this approach can be overkill. For those cases, we encourage you to use the Slots feature instead. Using slots gives your team the flexibility to change the content or personalization rules whenever needed without touching the component code.
To render a slot, all you need to do is provide the id
you configured in your Croct workspace. Based on the
slot's personalization rules and the user's context, the component will decide which content show to that user.
Notice that there's no logic on the client-side, meaning that your marketing or product team can freely change the
slot content as they need without requiring an update to your React app.
For the next example, we assume that you have already defined a slot with id home-banner
in your Croct workspace
with the following structure:
type HomeBanner = {
title: string,
subtitle: string,
cta: {
label: string,
link: string,
},
};
To render the content of the slot, you can either use the <Slot />
component or the useContent
hook.
Here's how to use the <Slot />
component:
import {ReactElement, Suspense} from 'react';
import {Slot} from '@croct/plug-react';
export default function OnboardingPage(): ReactElement {
return (
<Suspense fallback="โจ Personalizing content...">
<Slot id="home-banner">
{({title, subtitle, cta}: HomeBanner) => (
<div>
<strong>{title}</strong>
<p>{subtitle}</p>
<a href={cta.link}>{cta.label}</a>
</div>
)}
</Slot>
</Suspense>
)
}
To avoid the component from suspending while loading, you can provide an initial
state to be rendered instead:
import {ReactElement} from 'react';
import {Slot} from '@croct/plug-react';
export default function OnboardingPage(): ReactElement {
return (
<Slot id="home-banner" initial={null}>
{(props: HomeBanner|null) => (
props === null
? 'โจ Personalizing...'
: (
<div>
<strong>{title}</strong>
<p>{subtitle}</p>
<a href={cta.link}>{cta.label}</a>
</div>
)
)}
</Slot>
)
}
And here's an example using the useContent
hook:
import {ReactElement, Suspense} from 'react';
import {useContent} from '@croct/plug-react';
function HomeBanner(): ReactElement {
const banner = useContent<HomeBanner>('home-banner');
return (
<div>
<strong>{title}</strong>
<p>{subtitle}</p>
<a href={cta.link}>{cta.label}</a>
</div>
)
}
export default function HomePage(): ReactElement {
return (
<Suspense fallback="Personalizing content...">
<HomeBanner/>
</Suspense>
)
}
The following example shows how you can specify a fallback state for the home-banner
slot:
import {ReactElement, Suspense} from 'react';
import {Slot, useContent} from '@croct/plug-react';
const fallbackBanner: HomeBanner = {
title: 'Default title',
subtitle: 'Default subtitle',
cta: {
label: 'Try now',
link: 'https://croct.com',
}
};
function HomeBanner(): ReactElement {
const {title, subtitle, cta} = useContent<HomeBanner>('home-banner', {fallback: fallbackBanner});
return (
<div>
<strong>{title}</strong>
<p>{subtitle}</p>
<a href={cta.link}>{cta.label}</a>
</div>
)
}
export default function HomePage(): ReactElement {
return (
<Suspense fallback="Personalizing content...">
{/* Using the <Slot /> component */}
<Slot id="home-banner" fallback={fallbackBanner}>
{({title, subtitle, cta}: HomeBanner) => (
<div>
<strong>{title}</strong>
<p>{subtitle}</p>
<a href={cta.link}>{cta.label}</a>
</div>
)}
</Slot>
{/* Using the useContent hook */}
<HomeBanner />
</Suspense>
)
}
Again, we strongly recommend always providing a value for the fallback
property. For a full list of the available options,
please refer to the API documentation.
In the previous examples, you may have noticed that we specified the content type in the userFetch
call and in the
<Slot />
component's render function to have the benefit of strong typing.
For an even more robust approach, you can also declare the type of all available slots in a single declaration file using module augmentation as follows:
// slots.d.ts
import {NullableJsonObject} from '@croct/plug/sdk/json';
import {HomeBanner} from './HomePage';
declare module '@croct/plug/fetch' {
interface SlotMap extends Record<string, NullableJsonObject> {
'home-banner': HomeBanner;
}
}
If you use an IDE with Typescript code completion support, you will get autocomplete suggestions for slot IDs and content properties as a bonus:
You can use the same components and hooks on the server-side by simply providing an initial
state which is used to
pre-render on the server - the personalization happens transparently on the client during the initial render.
That means it's SEO friendly and can be cached with no performance overhead.
Notice that the methods exposed by the Plug work only on the client-side. Therefore, if you are using useCroct
,
the operations have to be executed inside the useEffect
hook or client-side callbacks, such as onClick
or onChange
, for example.
This library is built on top of the PlugJS. You can access the Plug instance through the useCroct
hook to track events,
login and logout users, and more.
In the following example we use the useCroct
to get the Plug instance and set an attribute to the user profile:
import {ReactElement, useCallback} from 'react';
import {useCroct} from '@croct/plug-react';
export default function DeveloperButton(): ReactElement {
const croct = useCroct();
const setPersona = useCallback(
() => croct.user.edit()
.set('custom.persona', 'developer')
.save(),
[croct],
);
return (<button onClick={setPersona}>I'm a developer</button>);
}
This reference documents all components available in the library.
The <CroctProvider />
component leverages React's Context API to
make a configured Plug instance available throughout
a React component tree.
The component takes the followings properties:
Option | Type | Required | Default Value | Description |
---|---|---|---|---|
appId |
string | Yes | None | The ID of the application you set up on Croct. |
debug |
boolean | No | false |
If true , turns on debug mode, which logs helpful messages to the console. |
track |
boolean | No | true |
If true , enables the automatic event tracking on initialization. |
token |
string|null | No | None | The JWT token issued by Croct. If null , clears any token specified on previous calls. |
userId |
string | No | None | The ID of the user logged into the application. Internally, the SDK will issue a token using the specified ID as the subject claim of the token. The token and userId options are mutually exclusive. |
tokenScope |
string | No | global |
Defines how the SDK should synchronize the token across multiple tabs, see token scopes for more details. |
eventMetadata |
JSON | No | None | Any additional information that may be useful to include as part of the event metadata. A common use case is to record the version of the application for future reference. |
logger |
object | No | None | A custom logger to handle log messages. By default, all logs are suppressed. |
urlSanitizer |
function | No | None | A function to sanitize URLs that allows removing sensitive information from URLs, such as tokens, that should not be sent to the platform. |
trackerEndpointUrl |
string | No | None | The URL of the tracker service, used by Croct's development team for testing purposes. |
evaluationEndpointUrl |
string | No | None | The URL of the evaluation service, used by Croct's development team for testing purposes. |
bootstrapEndpointUrl |
string | No | None | The URL of the bootstrap service, used by Croct's development team for testing purposes. |
Here's a simple example showing how to initialize the Plug instance:
import {CroctProvider} from '@croct/plug-react';
function App() {
return (
<CroctProvider appId="00000000-0000-0000-0000-000000000000">
<div>
<h1>My first personalized app ๐</h1>
</div>
</CroctProvider>
);
}
The <Personalization />
component evaluates and renders a CQL query.
The component takes the followings properties:
Option | Type | Required | Description |
---|---|---|---|
expression |
string | Yes | The CQL query to evaluate. |
children |
Function | Yes | A callback to render the result. |
fallback |
Result | No | A value to render when the evaluation fails. If not specified, the hook will throw an exception in case of failures. |
initial |
Result | SSR only | A value to render while loading, required for server-side rendering. If not specified, the rendering will suspend. |
timeout |
number | No | The maximum evaluation time in milliseconds. Once reached, the evaluation will fail. |
attributes |
JSON | No | A map of attributes to inject in the evaluation context. For example, passing the attributes {cities: ['New York', 'San Francisco']} you can reference them in expressions like context's cities include location's city . |
cacheKey |
string | No | An identifier that allows keeping the cached result separate from other cached items. By default, the cache key is formed from the expression and attributes. |
expiration |
number | No | The cache expiration time in milliseconds, extended on every render. If negative, the cache never expires. By default, the cache lifespan is set to 60000 (1 minute). |
Here's a simple example showing how to evaluate the user's persona:
import {ReactElement} from 'react';
import {Personalization} from '@croct/plug-react';
function PersonaBadge(): ReactElement {
return (
<Personalization expression="user's persona or else 'unknown'">
{persona => (<span>{persona}</span>)}
</Personalization>
);
}
The <Slot />
component fetches and renders a slot.
The component takes the followings properties:
Option | Type | Required | Description |
---|---|---|---|
id |
string | Yes | The ID of the slot to fetch. |
children |
Function | Yes | A callback to render the result. |
fallback |
Result | No | A value to render when the fetch fails. If not specified, the hook will throw an exception in case of failures. |
initial |
Result | SSR only | A value to render while loading, required for server-side rendering. If not specified, the rendering will suspend. |
cacheKey |
string | No | An identifier that allows keeping the cached result separate from other cached items. By default, the cache key is formed from the expression and attributes. |
expiration |
number | No | The cache expiration time in milliseconds, extended on every render. If negative, the cache never expires. By default, the cache lifespan is set to 60000 (1 minute). |
Here's a simple example showing how to render a banner in a slot:
import {ReactElement} from 'react';
import {Slot} from '@croct/plug-react';
function HeroBanner(): ReactElement {
return (
<Slot id="hero">
{({title, subtitle}) => (
<div>
<h1>{title}</h1>
<p>{subtitle}</p>
</div>
)}
</Slot>
);
}
This reference documents all hooks available in the library.
The useCroct
hook provides access to the Plug instance.
The hook has the following signature:
useCroct(): Plug
Here's a simple example showing how anonymize a user:
import {ReactElement, useCallback} from 'react';
import {useCroct} from '@croct/plug-react';
function LogoutButton(): ReactElement {
const croct = useCroct();
const anonymize = useCallback(() => croct.anonymize(), [croct]);
return <button type="button" onClick={anonymize}>Logout</button>
}
The useEvaluation
hook evaluates a CQL query.
The hook has the following signature:
function useEvaluation<Result extends JsonValue>(expression: string, options: Options = {}): Result
These are the currently supported options:
Option | Type | Description |
---|---|---|
fallback |
Result | The value returned when the evaluation fails. If not specified, the hook will throw an exception in case of failures. |
timeout |
number | The maximum evaluation time in milliseconds. Once reached, the evaluation will fail. |
attributes |
JSON | The map of attributes to inject in the evaluation context. For example, passing the attributes {cities: ['New York', 'San Francisco']} you can reference them in expressions like context's cities include location's city . |
cacheKey |
string | An identifier that allows keeping the cached result separate from other cached items. By default, the cache key is formed from the expression and attributes. |
expiration |
number | The cache expiration time in milliseconds, extended on every render. If negative, the cache never expires. By default, the cache lifespan is set to 60000 (1 minute). |
Here's a simple example showing how to evaluate the user's persona:
import {ReactElement} from 'react';
import {useEvaluation} from '@croct/plug-react';
function PersonaBadge(): ReactElement {
const persona = useEvaluation<string>("user's persona or else 'unknown'", {fallback: 'unknown'});
return <span>{persona}</span>
}
The useContent
hook fetches the content of a slot.
The hook has the following signature:
function useContent<Content extends NullableJsonObject>(slotId: string, options: Options = {}): Content
These are the currently supported options:
Option | Type | Description |
---|---|---|
fallback |
Content | The content returned when the fetch fails. If not specified, the hook will throw an exception in case of failures. |
cacheKey |
string | An identifier that allows keeping the cached content separate from other cached items. By default, the cache key is formed from the slot ID. |
expiration |
number | The cache expiration time in milliseconds, extended on every render. If negative, the cache never expires. By default, the cache lifespan is set to 60000 (1 minute). |
Here's a simple example showing how to fetch the content for a banner:
import {ReactElement} from 'react';
import {useContent} from '@croct/plug-react';
function HeroBanner(): ReactElement {
const {title, subtitle} = useContent<HeroBanner>('hero');
return (
<div>
<h1>{title}</h1>
<p>{subtitle}</p>
</div>
);
}
If this documentation has not answered all your questions, don't worry. Here are some alternative ways to get help from the Croct community.
Someone else from the community may have already asked a similar question or may be able to help with your problem.
The Croct team will also monitor posts with the "croct" tag. If there aren't any existing questions that help, please ask a new one.
If you have what looks like a bug, or you would like to make a feature request, please open a new issue on GitHub.
Before you file an issue, a good practice is to search for issues to see whether others have the same or similar problems. If you are unable to find an open issue addressing the problem, then feel free to open a new one.
Many people from the Croct community hang out on the Croct Slack Group. Feel free to join us and start a conversation.
This project is released under the MIT License.