Using JavaScript API to interact with NEAR

Quick Reference

• Installation
• Interacting with the Wallet
• Accounts
• Contracts
• Utilities

What is near-api-js

near-api-js is a complete library to interact with the NEAR blockchain. You can use it in the browser, or in Node.js runtime.

You'll typically first create a connection to NEAR with connect using a KeyStore. With the connection object you now can:

• Interact with the Wallet in a browser.
• Instantiate an Account object to:
  • Send tokens
  • Deploy contracts
  • Inspect, create or delete accounts
  • Manage keys for accounts.
• Instantiate a Contract object to call smart contract methods.

The library also contains some utility functions.

提示

To quickly get started with integrating NEAR in a web browser, read our Web Frontend integration article.

信息

Note the difference between near-api-js and near-sdk-js:

The JavaScript SDK is a library for developing smart contracts. It contains classes and functions you use to write your smart contract code.

The JavaScript API is a complete library for all possible commands to interact with NEAR. It’s a wrapper for the RPC endpoints, a library to interact with NEAR Wallet in the browser, and a tool for keys management.

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Install

Include near-api-js as a dependency in your package.

npm i --save near-api-js

Import

You can use the API library in the browser, or in Node.js runtime. Some features are available only in one of the environments. For example, the WalletConnection is only for the browser, and there are different KeyStore providers for each environment.

Browser

import * as nearAPI from "near-api-js";

Node

const nearAPI = require("near-api-js");

Key Store

If you sign transactions, you need to create a Key Store. In the browser, the LocalStorage KeyStore will be used once you ask your user to Sign In with the Wallet.

Using Browser

// creates keyStore using private key in local storage

const { keyStores } = nearAPI;
const myKeyStore = new keyStores.BrowserLocalStorageKeyStore();

Class BrowserLocalStorageKeyStore

Using Credentials Directory

// creates a keyStore that searches for keys in .near-credentials
// requires credentials stored locally by using a NEAR-CLI command: `near login`
// https://docs.near.org/tools/cli#near-login

const { keyStores } = nearAPI;
const homedir = require("os").homedir();
const CREDENTIALS_DIR = ".near-credentials";
const credentialsPath = require("path").join(homedir, CREDENTIALS_DIR);
const myKeyStore = new keyStores.UnencryptedFileSystemKeyStore(credentialsPath);

Class UnencryptedFileSystemKeyStore

Using a File

// creates keyStore from a provided file
// you will need to pass the location of the .json key pair

const { KeyPair, keyStores } = require("near-api-js");
const fs = require("fs");
const homedir = require("os").homedir();

const ACCOUNT_ID = "near-example.testnet"; // NEAR account tied to the keyPair
const NETWORK_ID = "testnet";
// path to your custom keyPair location (ex. function access key for example account)
const KEY_PATH = "/.near-credentials/near-example-testnet/get_token_price.json";

const credentials = JSON.parse(fs.readFileSync(homedir + KEY_PATH));
const myKeyStore = new keyStores.InMemoryKeyStore();
myKeyStore.setKey(
  NETWORK_ID,
  ACCOUNT_ID,
  KeyPair.fromString(credentials.private_key)
);

Class InMemoryKeyStore     Class KeyPair

Using a private key string

// creates keyStore from a private key string
// you can define your key here or use an environment variable

const { keyStores, KeyPair } = nearAPI;
const myKeyStore = new keyStores.InMemoryKeyStore();
const PRIVATE_KEY =
  "by8kdJoJHu7uUkKfoaLd2J2Dp1q1TigeWMG123pHdu9UREqPcshCM223kWadm";
// creates a public / private key pair using the provided private key
const keyPair = KeyPair.fromString(PRIVATE_KEY);
// adds the keyPair you created to keyStore
await myKeyStore.setKey("testnet", "example-account.testnet", keyPair);

Class InMemoryKeyStore     Class KeyPair

Connecting to NEAR

The object returned from connect is your entry-point for all commands in the API. To sign a transaction you'll need a KeyStore to create a connection.

TestNet

const { connect } = nearAPI;

const connectionConfig = {
  networkId: "testnet",
  keyStore: myKeyStore, // first create a key store
  nodeUrl: "https://rpc.testnet.near.org",
  walletUrl: "https://testnet.mynearwallet.com/",
  helperUrl: "https://helper.testnet.near.org",
  explorerUrl: "https://testnet.nearblocks.io",
};
const nearConnection = await connect(connectionConfig);

MainNet

const { connect } = nearAPI;

const connectionConfig = {
  networkId: "mainnet",
  keyStore: myKeyStore, // first create a key store
  nodeUrl: "https://rpc.mainnet.near.org",
  walletUrl: "https://wallet.mainnet.near.org",
  helperUrl: "https://helper.mainnet.near.org",
  explorerUrl: "https://nearblocks.io",
};
const nearConnection = await connect(connectionConfig);

LocalNet

const { connect } = nearAPI;
const connectionConfig = {
  networkId: "local",
  nodeUrl: "http://localhost:3030",
  walletUrl: "http://localhost:4000/wallet",
};
const nearConnection = await connect(connectionConfig);

Module connect

RPC Failover

RPC providers can experience intermittent downtime, connectivity issues, or rate limits that cause client transactions to fail. This can be prevented by using the FailoverRpcProvider that supports multiple RPC providers.

MainNet

const jsonProviders = [
  new JsonRpcProvider({
    url: 'https://rpc.mainnet.near.org',
  }),
  new JsonRpcProvider(
    {
      url: 'https://another-rpc.cloud.com',
      headers: { 'X-Api-Key': 'some string' },
    },
    { retries: 3, backoff: 2, wait: 500 }
  ),
];
const provider = new FailoverRpcProvider(jsonProviders);

await connect({
  networkId: 'mainnet',
  provider: provider,
  // this isn't used if `provider` is specified, but is still required for backward compatibility
  nodeUrl: 'https://rpc.mainnet.near.org',
});

Class FailoverRpcProvider