Typing
If you are using TypeScript in your project, you can leverage LiveObjects' built-in TypeScript support to ensure type safety and enable autocompletion when working with objects on a channel.
Global AblyObjectsTypes interface
You can type objects on all your channels by defining a global AblyObjectsTypes interface. If you only want to type the root object for a specific channel, see the Typing channel.objects.getRoot() section below.
Define the AblyObjectsTypes interface in a type declaration file. You can create a file named ably.config.d.ts in the root of your application:
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// file: ably.config.d.ts
import { LiveCounter, LiveMap } from 'ably';
// Define dedicated types and export them for reuse in your application
export type MyCustomRoot = {
reactions: LiveMap<{
hearts: LiveCounter;
likes: LiveCounter;
}>;
};
declare global {
export interface AblyObjectsTypes {
root: MyCustomRoot;
}
}This enables TypeScript to infer the correct types when accessing and mutating LiveObjects:
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// LiveMap<{ reactions: LiveMap<{ hearts: LiveCounter; likes: LiveCounter }> }>
const root = await channel.objects.getRoot();
// LiveMap<{ hearts: LiveCounter; likes: LiveCounter }>
const reactions = root.get('reactions');
// LiveCounter
const likes = reactions.get('likes');
reactions.set('hearts', 1); // Error: Argument of type 'number' is not assignable to parameter of type 'LiveCounter'.ts(2345)Typing channel.objects.getRoot()
You can pass a type parameter directly to the channel.objects.getRoot<T>() method call to type the root object for a channel explicitly:
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// Define types for different root objects
type ReactionsRoot = {
hearts: LiveCounter;
likes: LiveCounter;
};
type PollsRoot = {
currentPoll: LiveMap;
};
// LiveMap<{ hearts: LiveCounter; likes: LiveCounter }>
const reactionsRoot = await reactionsChannel.objects.getRoot<ReactionsRoot>();
// LiveMap<{ currentPoll: LiveMap }>
const pollsRoot = await pollsChannel.objects.getRoot<PollsRoot>();Typing channel.objects.getRoot<T>() is particularly useful when your application uses multiple channels, each with a different object structure.