JavaScript SDK

shell
# npm
npm install polkamarkets-js

# yarn
yarn add polkamarkets-js

javascript
import * as polkamarketsjs from 'polkamarkets-js';

javascript
const polkamarkets = new polkamarketsjs.Application({
  web3Provider,
  web3EventsProvider,
  web3PrivateKey
});

javascript
await service.login(); // triggers polkamarkets to connect user wallet

javascript
const userAddress = await polkamarkets.getAddress();
console.log(`User is logged in as: ${address}`);

javascript
import * as polkamarketsjs from 'polkamarkets-js';

// Example snippet:
// 1) You've already instantiated `polkamarkets` (see the prior docs).
// 2) Now get the prediction market V3 contract:
const pm = polkamarkets.getPredictionMarketV3PlusContract({
  contractAddress: '0x1234...',       // actual PM contract
  querierContractAddress: '0xabcd...' // optional, if you have a read-only/querier contract
});

javascript
// the following method is used to calculate how many shares the user wants to purchase
const minOutcomeSharesToBuy = await pm.calcBuyAmount({
	marketId,
	outcomeId,
	value
});

await pm.buy({
  marketId,             // e.g. "123"
  outcomeId,            // e.g. 1 (Yes)
  value,                // e.g. 100
  minOutcomeSharesToBuy // slippage protection
  wrapped               // true/false (if using ETH or an ERC20 token)
});

// alternatively, if we have a referral code, we can call referralBuy
await pm.referralBuy({
  marketId,             // e.g. "123"
  outcomeId,            // e.g. 1 (Yes)
  value,                // e.g. 100
  minOutcomeSharesToBuy // slippage protection
  code                  // referral code
});

javascript
// the following method is used to calculate how many shares the user wants to sell
const maxOutcomeSharesToSell = await pm.calcSellAmount({
	marketId,
	outcomeId,
	value
});

await pm.sell({
  marketId,
  outcomeId,
  value,                  // e.g. 50 tokens
  maxOutcomeSharesToSell, // slippage
  wrapped
});

// alternatively, if we have a referral code, we can call referralSell
await pm.referralSell({
  marketId,
  outcomeId,
  value,                  // e.g. 50 tokens
  maxOutcomeSharesToSell, // slippage
  code
});

javascript
await pm.claimWinnings({
  marketId,             // e.g. "123"
  wrapped               // true/false (if using ETH or an ERC20 token)
});

javascript
await pm.claimVoidedOutcomeShares({
  marketId,
  outcomeId,
  wrapped
});

javascript
const portfolio = await pm.getPortfolio({
	user
});

console.log(portfolio);
// Example response:
// {
//   ..,
//   20: {
//     liquidity: {
//       shares: 1000,
//       price: 0.89035,
//     },
//     outcomes: {
//       0: {
//         shares: 1591.87,
//         price: 0.6281,
//         voidedWinningsToClaim: false,
//         voidedWinningsClaimed: false,
//       },
//       1: {
//         shares: 0,
//         price: 0,
//         voidedWinningsToClaim: false,
//         voidedWinningsClaimed: false,
//       }
//     }
//     claimStatus: {
//       winningsToClaim: false,
//       winningsClaimed: false,
//       liquidityToClaim: false,
//       liquidityClaimed: false,
//       voidedWinningsToClaim: false,
//       voidedWinningsClaimed: false,
//     }
//   },
//   ...
// }

javascript
const prices = await pm.getMarketPrices({
	marketId
});

console.log(prices);
// Example response:
// {
//     "liquidity": 0.6181712323806557,
//     "outcomes": {
//         "0": 0.8930217320508439,
//         "1": 0.10697826794915608
//     }
// }

• Market ERC20 decimals

• User market positions

• Market outcome prices

javascript
const erc20 = polkamarkets.getERC20Contract({
  contractAddress: '0xYOUR_ERC20_TOKEN_ADDRESS'
});

javascript
await erc20.isApproved({
	address: polkamarkets.getAddress(),
  amount,
  spenderAddress
});

javascript
await erc20.approve({
	address,
	amount
});

1. Initialize Polkamarkets with a web3Provider and web3PrivateKey.

2. Instantiate a Prediction Market V3 contract (pm) and an ERC20 contract (erc20).

3. Check approval, approve if needed, create a market, buy outcome shares, and finally claim winnings.

javascript
import * as polkamarketsjs from 'polkamarkets-js';

// 1) Initialize polkamarkets
const polkamarkets = new polkamarketsjs.Application({
  web3Provider: 'api.mainnet.abs.xyz',
  web3PrivateKey: '', // add your pk here
});

// 2) Get the Prediction Market V3 contract
const pm = polkamarkets.getPredictionMarketV3PlusContract({
  contractAddress: '0x3e0F5F8F5Fb043aBFA475C0308417Bf72c463289',   // pmContractAddress
  querierContractAddress: '0x1d5773Cd0dC74744C1F7a19afEeECfFE64f233Ff' // pmQuerierAddress (optional)
});

// 3) Get the ERC20 contract
const erc20 = polkamarkets.getERC20Contract({
  contractAddress: '0x84a71ccd554cc1b02749b35d22f684cc8ec987e1' // erc20Address
});

// 4) (Optional) Log in (not strictly required if using private key, but included for completeness)
await polkamarkets.login();

// 5) Grab current user address
const userAddress = await polkamarkets.getAddress();
console.log('User address:', userAddress);

// 6) Check allowance for the pm contract
const neededAmount = '100000000'; 
const spender = '0x4f4988A910f8aE9B3214149A8eA1F2E4e3Cd93CC';

const approved = await erc20.isApproved({
  address: userAddress,
  spenderAddress: spender,
  amount: neededAmount
});

if (!approved) {
  console.log('Not enough allowance; approving now...');
  await erc20.approve({
    address: userAddress,
    amount: neededAmount,
    spenderAddress: spender
  });
  console.log('Approval successful!');
} else {
  console.log('Sufficient allowance already exists.');
}

// 7) Buy some outcome shares of a marketId
const marketId = 123; // the market id you want to purchase shares
const outcomeId = 0; // the market id you want to purchase shares
const value = 10; // the amount (in human format, it is converted to the correct decimals in the function)
const minOutcomeSharesToBuy = await pm.calcBuyAmount({
	marketId,
	outcomeId,
	value
});


await pm.buy({
  marketId,
  outcomeId,
  value,
  minOutcomeSharesToBuy
});
console.log('Bought outcome shares!');
const portfolio = await pm.getPortfolio({ user: userAddress });
console.log(portfolio);

// 9) (Later) Claim winnings (assumes market eventually resolves in your favor)
// ...
// await pm.claimWinnings(marketId);
// console.log('Winnings claimed!');

1. Initialization: We pass a web3Provider (api.mainnet.abs.xyz) and a random web3PrivateKey for direct signing, plus isSocialLogin: false to skip the wallet UI.

2. Contracts:
• pm is our Prediction Market V3 instance.
• erc20 is the token contract used for buying shares or adding liquidity.

3. Login: If you prefer a standard wallet approach (Metamask, etc.), remove web3PrivateKey and set isSocialLogin: true; calling await polkamarkets.login() triggers the wallet flow.

4. Approval: We check if the user has at least neededAmount allowance for the PM contract, then approve if needed.

5. Buy: We purchase outcome 0 with '50000000' units of the token. Adjust to match your token’s decimals.

6. Claim: Eventually, after resolution, you might call pm.claimWinnings(marketId) if you hold the winning outcome.