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Connectors are functions that encapsulate the business logic of widgets, separating it from the rendering layer. This makes the same search logic reusable across different frameworks and rendering approaches.

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What is a connector?

A connector is a function that:
  1. Handles all search-related logic (parameters, state management)
  2. Accepts a render function from you
  3. Returns a widget factory function
  4. Calls your render function with a simplified API
The connector pattern allows you to build custom widgets without reimplementing search logic.

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Connector vs Widget

Understanding the difference:

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Widget

  • Complete UI component
  • Combines logic and rendering
  • Framework-specific
  • Ready to use out of the box
// Pre-built widget
import { searchBox } from 'instantsearch.js/es/widgets';

searchBox({
  container: '#searchbox',
  placeholder: 'Search...'
})

​
Connector

  • Business logic only
  • You provide the rendering
  • Framework-agnostic
  • Maximum customization
// Connector + custom render
import { connectSearchBox } from 'instantsearch.js/es/connectors';

connectSearchBox(
  (renderOptions, isFirstRender) => {
    // Your custom rendering
  }
)

​
How connectors work

The connector pattern is defined in /home/daytona/workspace/source/packages/instantsearch.js/src/types/connector.ts:64-83: 
type Connector<TWidgetDescription, TConnectorParams> = <TWidgetParams>(
  renderFn: Renderer<TWidgetDescription['renderState'], TConnectorParams & TWidgetParams>,
  unmountFn?: Unmounter
) => (widgetParams: TConnectorParams & TWidgetParams) => Widget<TWidgetDescription>;
In practice:
1

Call the connector

Pass your render function to the connector.
const mySearchBox = connectSearchBox(
  (renderOptions, isFirstRender) => {
    // Rendering logic
  }
);
2

Configure the widget

The connector returns a widget factory. Call it with your parameters.
const searchBoxWidget = mySearchBox({
  // Your custom parameters
  placeholder: 'Search products...'
});
3

Add to InstantSearch

Use the widget like any other.
search.addWidgets([searchBoxWidget]);

​
Render function API

Your render function receives two arguments (from /home/daytona/workspace/source/packages/instantsearch.js/src/types/connector.ts:43-53):

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Render options

The first argument contains widget-specific data plus base options: 
type RendererOptions<TWidgetParams> = {
  widgetParams: TWidgetParams;           // Your widget parameters
  instantSearchInstance: InstantSearch;   // The main instance
  results?: SearchResults;                // Search results
  hits?: Hit[];                          // Result hits
  insights?: InsightsClient;             // Insights client
  // ... plus connector-specific options
};

​
Is first render

The second argument is a boolean indicating if this is the initial render: 
function render(renderOptions, isFirstRender) {
  if (isFirstRender) {
    // Create DOM elements, set up event listeners
  } else {
    // Update existing elements with new data
  }
}

​
Using connectors

Here’s a complete example using connectSearchBox (based on /home/daytona/workspace/source/packages/instantsearch.js/src/connectors/search-box/connectSearchBox.ts): 
import { connectSearchBox } from 'instantsearch.js/es/connectors';

const customSearchBox = connectSearchBox(
  (renderOptions, isFirstRender) => {
    const { query, refine, clear, widgetParams } = renderOptions;
    const { container } = widgetParams;
    
    if (isFirstRender) {
      // Create the HTML structure
      const input = document.createElement('input');
      const button = document.createElement('button');
      
      input.placeholder = 'Search...';
      button.textContent = 'Clear';
      
      // Set up event listeners
      input.addEventListener('input', (e) => {
        refine(e.target.value);
      });
      
      button.addEventListener('click', () => {
        clear();
        input.value = '';
      });
      
      container.appendChild(input);
      container.appendChild(button);
    }
    
    // Update the input value
    const input = container.querySelector('input');
    input.value = query;
  },
  
  // Optional unmount function
  () => {
    const container = document.querySelector('#searchbox');
    container.innerHTML = '';
  }
);

// Use the custom widget
search.addWidgets([
  customSearchBox({
    container: document.querySelector('#searchbox'),
  })
]);

​
SearchBox connector example

The SearchBox connector provides these render options (from /home/daytona/workspace/source/packages/instantsearch.js/src/connectors/search-box/connectSearchBox.ts:34-54): 
type SearchBoxRenderState = {
  query: string;                    // Current search query
  refine: (value: string) => void;  // Function to update query
  clear: () => void;                // Function to clear query
  isSearchStalled: boolean;         // Whether search is stalled
};
Example implementation: 
const { query, refine, clear } = renderOptions;

// Display current query
console.log('Current query:', query);

// Update the query
refine('new search term');

// Clear the search
clear();

​
Hits connector example

The Hits connector provides search results (from /home/daytona/workspace/source/packages/instantsearch.js/src/connectors/hits/connectHits.ts:31-62): 
type HitsRenderState<THit> = {
  hits: Array<Hit<THit>>;           // Deprecated, use items
  items: Array<Hit<THit>>;          // Matched results
  results?: SearchResults;           // Full results object
  banner?: Banner;                  // Optional banner
  sendEvent: SendEventForHits;      // Send Insights events
  bindEvent: BindEventForHits;      // Bind Insights events
};
Example: 
import { connectHits } from 'instantsearch.js/es/connectors';

const customHits = connectHits(
  (renderOptions, isFirstRender) => {
    const { items, results, sendEvent, widgetParams } = renderOptions;
    const { container } = widgetParams;
    
    if (isFirstRender) {
      const div = document.createElement('div');
      div.className = 'hits-container';
      container.appendChild(div);
    }
    
    const hitsContainer = container.querySelector('.hits-container');
    
    hitsContainer.innerHTML = items.map(hit => `
      <article>
        <h2>${hit.name}</h2>
        <p>${hit.description}</p>
        <button onclick="${() => sendEvent('click', hit, 'Product Clicked')}">View</button>
      </article>
    `).join('');
    
    // Send automatic view events
    sendEvent('view', items);
  }
);

​
Available connectors

InstantSearch provides connectors for all major widgets:
  • connectSearchBox - Search input logic
  • connectHits - Results display logic
  • connectInfiniteHits - Infinite scroll logic
  • connectStats - Search statistics
  • connectPagination - Pagination logic
  • connectAutocomplete - Autocomplete logic
  • connectRefinementList - Multi-select facets
  • connectMenu - Single-select facets
  • connectHierarchicalMenu - Category hierarchy
  • connectRange - Numeric range filter
  • connectRatingMenu - Star rating filter
  • connectToggleRefinement - Boolean toggle
  • connectNumericMenu - Numeric menu
  • connectConfigure - Search parameters
  • connectGeoSearch - Geographic search
  • connectPoweredBy - Algolia branding
  • connectQueryRules - Query rules
  • connectRelatedProducts - Related items
  • connectFrequentlyBoughtTogether - Product bundles
  • connectTrendingItems - Trending content
  • connectLookingSimilar - Similar items

​
Connector parameters

Connectors can accept their own parameters. For example, connectSearchBox accepts: 
type SearchBoxConnectorParams = {
  queryHook?: (query: string, hook: (value: string) => void) => void;
};
Use this for debouncing: 
import { connectSearchBox } from 'instantsearch.js/es/connectors';

const debouncedSearchBox = connectSearchBox(
  (renderOptions, isFirstRender) => {
    // Your render logic
  }
);

search.addWidgets([
  debouncedSearchBox({
    container: '#searchbox',
    queryHook(query, search) {
      clearTimeout(timerId);
      timerId = setTimeout(() => search(query), 300);
    },
  })
]);

​
When to use connectors

Use connectors when

  • Building custom UI components
  • Creating framework-specific widgets
  • Need full control over rendering
  • Building design system components
  • Implementing unique interactions

Use pre-built widgets when

  • Standard search UI is sufficient
  • Rapid prototyping
  • Using default themes
  • Limited customization needed
  • Following best practices

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Best practices

Clean up in the unmount function: Always provide an unmount function to remove event listeners and clean up DOM elements.
connectSearchBox(
  renderFn,
  () => {
    // Remove event listeners
    // Clear DOM elements
  }
)
Use isFirstRender efficiently: Only create DOM elements and set up event listeners on the first render. Update existing elements on subsequent renders.
Type your connectors: In TypeScript, use generic types for better type safety:
type ProductHit = {
  name: string;
  price: number;
};

const customHits = connectHits<ProductHit>(
  ({ items }) => {
    // items is typed as Array<Hit<ProductHit>>
  }
);

Widgets

Learn about the widget system

Custom widgets guide

Step-by-step widget creation

Connector API reference

Complete connector documentation

Search state

Understanding UI state management

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