An easy-to-use JavaScript API for the Internet Computer.
npm install ic0ic0   > ### An easy-to-use JavaScript API for the Internet Computer.
---
The ic0 package is a simple, straightfoward way to interact with canisters running on the Internet Computer (IC).
``sh`
npm i --save ic0
Try running the following code from Node.js or a web application:
`ts
import ic from 'ic0';
const ledger = ic('ryjl3-tyaaa-aaaaa-aaaba-cai'); // Ledger canister
console.log(await ledger.call('name')); // Call the name() method`
Easily call any Internet Computer canister using the following syntax:
`ts
import ic from 'ic0';
ic(canisterId).call(method, ...args); // IC mainnet
ic.local(canisterId).call(method, ...args); // Local replica
`
The dfx start command hosts a local execution environment for developing canister smart contracts. Here is an example of how to call a local canister:
`ts
const backend = ic.local('rrkah-fqaaa-aaaaa-aaaaq-cai'); // Access a local canister
backend.call('myFunction', 123); // Call myFunction(123)
`ts
const ledger = ic('ryjl3-tyaaa-aaaaa-aaaba-cai'); // Principal for the IC ledger
console.log(await ledger.call('name')); // => { name: 'Internet Computer' }
`
Replica canisters use agent-js behind the scenes.
`ts
import { replica, HttpAgent } from 'ic0';
const ic = replica(new HttpAgent({ ... })); // Use a custom agent from @dfinity/agent
const ledger = ic('ryjl3-tyaaa-aaaaa-aaaba-cai');
console.log(await ledger.call('name')); // => { name: 'Internet Computer' }
`
A mock canister makes it easy to mock the behavior of a canister.
`ts
import { mockCanister } from 'ic0';
const mock = mockCanister({
// Mock canister method named echo()
async echo(x: number) {
return x;
}
});
console.log(await mock.call('echo', 123)); // => 123
`
Provide a fallback canister and/or compose several mocks by passing a second argument to the mockCanister() function:
`ts
import { mockCanister, replicaCanister } from 'ic0';
const ledger = replicaCanister(principal, agent);
const mockLedger = mockCanister({
async echo(x: number) {
return x;
}
}, ledger); // Fall back to the deployed ledger canister
const mock = mockCanister({
async runMock() {
return this.call('echo', 456); // Call the mocked echo() function
}
}, mockLedger); // Fall back to another mock canister
console.log(await mock.call('runMock')); // => 456
``
Check out the following GitHub repositories for more IC-related npm packages:
- agent-js: a collection of npm packages for building on the Internet Computer
- node-motoko: run Motoko programs directly in the browser
- mo-dev: a live-reload server for local Motoko dapp development
- @infu/icblast: a community-built library for exploring the IC and writing integration tests