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getConfig()

Get configuration value synchronously from cache or defaults. 
grain.getConfig(key: string): string | undefined
Parameters:
  • key - Configuration key
Returns: Configuration value or undefined Example: 
const heroText = grain.getConfig('hero_text');
console.log(heroText); // Returns immediately
Behavior:
  • Returns cached value instantly
  • Returns default if provided
  • Returns undefined if not found
  • Triggers background refresh

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getAllConfigs()

Get all configurations synchronously. 
grain.getAllConfigs(): Record<string, string>
Returns: Object with all configuration key-value pairs Example: 
const configs = grain.getAllConfigs();
console.log(configs);
// { hero_text: "Welcome", button_color: "blue", ... }

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getConfigAsync()

Get configuration value asynchronously with cache-first strategy. 
await grain.getConfigAsync(
  key: string,
  options?: RemoteConfigOptions
): Promise<string | undefined>
Parameters:
  • key - Configuration key
  • options.properties - User properties for personalization
  • options.forceRefresh - Skip cache, fetch from API
  • options.immediateKeys - Keys to fetch immediately
Returns: Promise resolving to configuration value Example: 
// Basic usage
const value = await grain.getConfigAsync('hero_text');

// With personalization
const value = await grain.getConfigAsync('hero_text', {
  properties: {
    plan: 'premium',
    location: 'US'
  }
});

// Force refresh
const value = await grain.getConfigAsync('hero_text', {
  forceRefresh: true
});

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getAllConfigsAsync()

Get all configurations asynchronously. 
await grain.getAllConfigsAsync(
  options?: RemoteConfigOptions
): Promise<Record<string, string>>
Parameters:
  • options.properties - User properties for personalization
  • options.forceRefresh - Skip cache, fetch from API
Returns: Promise resolving to all configurations Example: 
// Basic usage
const configs = await grain.getAllConfigsAsync();

// With personalization
const configs = await grain.getAllConfigsAsync({
  properties: {
    plan: 'premium',
    location: 'US'
  }
});

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fetchConfig()

Fetch configurations directly from API. 
await grain.fetchConfig(
  options?: RemoteConfigOptions
): Promise<RemoteConfigResponse>
Parameters:
  • options.immediateKeys - Keys to fetch immediately
  • options.properties - User properties for personalization
  • options.userId - User ID override
Returns: Promise resolving to full API response Example: 
const response = await grain.fetchConfig({
  immediateKeys: ['hero_text', 'button_color'],
  properties: {
    plan: 'premium'
  }
});

console.log(response.configurations);
console.log(response.snapshotId);
console.log(response.qualifiedSegments);
Response includes:
  • configurations - Config key-value pairs
  • snapshotId - Configuration snapshot ID
  • qualifiedSegments - Matched user segments
  • qualifiedRuleSets - Matched rule sets
  • isFinal - Whether more configs may load
  • timestamp - Response timestamp

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preloadConfig()

Preload configurations for immediate synchronous access. 
await grain.preloadConfig(
  immediateKeys?: string[],
  properties?: Record<string, string>
): Promise<void>
Parameters:
  • immediateKeys - Specific keys to preload (optional, loads all if omitted)
  • properties - User properties for personalization
Returns: Promise that resolves when configs are loaded Example: 
// Preload specific keys
await grain.preloadConfig(['hero_text', 'button_color']);

// Now available synchronously
const heroText = grain.getConfig('hero_text');

// Preload all configs
await grain.preloadConfig();
When to use:
  • App startup
  • Before rendering UI
  • Critical configs needed immediately

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addConfigChangeListener()

Add listener for configuration changes. 
grain.addConfigChangeListener(
  listener: ConfigChangeListener
): void
Parameters:
  • listener - Callback function receiving updated configs
Example: 
const listener = (configurations) => {
  console.log('Configs updated:', configurations);
  // Update UI
};

grain.addConfigChangeListener(listener);
When listeners fire:
  • After background refresh completes
  • When manual refresh happens
  • When cache updates

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removeConfigChangeListener()

Remove configuration change listener. 
grain.removeConfigChangeListener(
  listener: ConfigChangeListener
): void
Parameters:
  • listener - Previously added listener function
Example: 
grain.removeConfigChangeListener(listener);
When to remove:
  • Component unmounts
  • No longer need updates
  • Cleanup on destroy

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Configuration Flow

Cache-first strategy:
  1. getConfig() returns cached value (instant)
  2. Background fetch starts automatically
  3. When fresh data arrives, listeners fire
  4. Cache updates for next access
Personalization: Pass properties to get user-specific values: 
const message = await grain.getConfigAsync('welcome_message', {
  properties: {
    plan: user.plan,
    signup_date: user.signupDate,
    location: user.country
  }
});
Rules in dashboard determine which values match which users.

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Next Steps

Remote Config

Learn configuration concepts

Core Methods

Event tracking methods