Near Smart Contract Js

2. Contract Template

// src/contract.ts
import { NearBindgen, near, call, view, initialize, LookupMap, UnorderedMap, NearPromise } from "near-sdk-js";

@NearBindgen({})
class Contract {
  owner_id: string = "";
  data: LookupMap<string> = new LookupMap<string>("d");

  @initialize({})
  init({ owner_id }: { owner_id: string }) {
    this.owner_id = owner_id;
  }

  @view({})
  get_value({ key }: { key: string }): string | null {
    return this.data.get(key);
  }

  @call({ payableFunction: true })
  set_value({ key, value }: { key: string; value: string }) {
    const sender = near.predecessorAccountId();
    this.data.set(key, value);
    near.log(`${sender} set ${key} = ${value}`);
  }

  @view({})
  get_owner(): string {
    return this.owner_id;
  }
}

3. Build

npx near-sdk-js build src/contract.ts build/contract.wasm

4. Test (with near-workspaces)

npm install --save-dev near-workspaces ava

// test/contract.ava.ts
import { Worker, NearAccount } from "near-workspaces";
import test from "ava";

let worker: Worker;
let root: NearAccount;
let contract: NearAccount;

test.before(async (t) => {
  worker = await Worker.init();
  root = worker.rootAccount;
  contract = await root.devDeploy("build/contract.wasm");
  await contract.call(contract, "init", { owner_id: root.accountId });
});

test.after.always(async () => { await worker.tearDown(); });

test("set and get value", async (t) => {
  await root.call(contract, "set_value", { key: "test", value: "42" });
  const result = await contract.view("get_value", { key: "test" });
  t.is(result, "42");
});

npx ava

5. Deploy

# Create account if needed
near account create-account fund-later use-auto-generation save-to-folder ~/.near-credentials/testnet/

# Deploy with init
near contract deploy <account-id> use-file build/contract.wasm \
  with-init-call init json-args '{"owner_id":"<owner>"}' \
  prepaid-gas '30 Tgas' attached-deposit '0 NEAR' \
  network-config testnet sign-with-keychain send

6. Interact

# View call (free)
near contract call-function as-read-only <contract-id> get_value \
  json-args '{"key":"test"}' network-config testnet now

# Change call (costs gas)
near contract call-function as-transaction <signer-id> <contract-id> set_value \
  json-args '{"key":"hello","value":"world"}' \
  prepaid-gas '30 Tgas' attached-deposit '0 NEAR' \
  network-config testnet sign-with-keychain send

Key Decorators

Collections

Common Patterns

• Access control: assert(near.predecessorAccountId() === this.owner_id, "Unauthorized")
• Deposit check: assert(near.attachedDeposit() > BigInt(0), "Requires deposit")
• Cross-contract: NearPromise.new("other.near").functionCall("method", args, deposit, gas)
• Events: near.log(JSON.stringify({ standard: "nep297", event: "...", data: [...] }))