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JavaScript and TypeScript library to interact with the Internet Computer for Node.js and Client applications

Visit the Dfinity Forum and SDK Documentation for more information and support building on the Internet Computer.

Additional API Documentation can be found here.


Using agent:

npm i --save @dfinity/agent

In the browser:

import * as agent from "@dfinity/agent";

or using individual exports:

import { Actor, HttpAgent } from "@dfinity/agent";

In Node.js

const actor = require("@dfinity/agent");

Using an Agent

The agent is a low-level interface that the Actor uses to encode and decode messages to the Internet Computer. It provides call, query and readState methods to the Actor, as well as a few additional utilities. For the most part, calls through the agent are intended to be structured through an Actor, configured with a canister interface that can be automatically generated from a Candid interface.

Initializing an Actor

The most common use for the agent is to create an actor. This is done by calling the Actor.createActor constructor:

Actor.createActor(interfaceFactory: InterfaceFactory, configuration: ActorConfig): ActorSubclass<T>

The interfaceFactory is a function that returns a runtime interface that the Actor uses to strucure calls to a canister. The interfaceFactory can be written manually, but it is recommended to use the dfx generate command to generate the interface for your project, or to use the didc tool to generate the interface for your project.

Inspecting an actor's agent

Use the Actor.agentOf method to get the agent of an actor:

const defaultAgent = Actor.agentOf(defaultActor);

This is useful if you need to replace or invalidate the identity used by an actor's agent.

For example, if you want to replace the identity of an actor's agent with a newly authenticated identity from Internet Identity, you can do so by calling the Actor.replaceAgent method:

defaultAgent.replaceIdentity(await authClient.getIdentity());

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