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Documentation Index

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getBalancesForBridge

Get user’s token balances across all supported chains for bridge operations. 
await sdk.getBalancesForBridge(): Promise<UserAsset[]>

​
Returns

​
assets
UserAsset[]
Array of user assets with balances across all chains

​
Example

const assets = await sdk.getBalancesForBridge();

console.log(`Found ${assets.length} tokens`);

assets.forEach(asset => {
  console.log(`${asset.symbol}: ${asset.balance} ($${asset.balanceInFiat})`);
  
  asset.breakdown.forEach(chain => {
    console.log(`  - ${chain.chain.name}: ${chain.balance}`);
  });
});

​
Response Example

[
  {
    "symbol": "USDC",
    "balance": "1250.50",
    "balanceInFiat": 1250.50,
    "decimals": 6,
    "icon": "https://...",
    "breakdown": [
      {
        "balance": "500.00",
        "balanceInFiat": 500.00,
        "chain": {
          "id": 1,
          "name": "Ethereum",
          "logo": "https://..."
        },
        "contractAddress": "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
        "decimals": 6,
        "symbol": "USDC"
      },
      {
        "balance": "750.50",
        "balanceInFiat": 750.50,
        "chain": {
          "id": 137,
          "name": "Polygon",
          "logo": "https://..."
        },
        "contractAddress": "0x3c499c3f21b113b72d1ce615b5b297a8c7c5a6e8",
        "decimals": 6,
        "symbol": "USDC"
      }
    ]
  },
  {
    "symbol": "ETH",
    "balance": "2.5",
    "balanceInFiat": 8750.00,
    "decimals": 18,
    "icon": "https://...",
    "breakdown": [
      {
        "balance": "1.5",
        "balanceInFiat": 5250.00,
        "chain": {
          "id": 1,
          "name": "Ethereum",
          "logo": "https://..."
        },
        "contractAddress": "0x0000000000000000000000000000000000000000",
        "decimals": 18,
        "symbol": "ETH"
      },
      {
        "balance": "1.0",
        "balanceInFiat": 3500.00,
        "chain": {
          "id": 42161,
          "name": "Arbitrum One",
          "logo": "https://..."
        },
        "contractAddress": "0x0000000000000000000000000000000000000000",
        "decimals": 18,
        "symbol": "ETH"
      }
    ]
  }
]

​
getBalancesForSwap

Get user’s token balances for swap operations. Optionally filter to only native tokens and stablecoins. 
await sdk.getBalancesForSwap(onlyNativesAndStables?: boolean): Promise<UserAsset[]>
​
onlyNativesAndStables
boolean
default:"false"
If true, returns only native tokens (ETH, MATIC, etc.) and stablecoins (USDC, USDT)

​
Returns

​
assets
UserAsset[]
Array of user assets (same structure as getBalancesForBridge)

​
Example

// Get all swap-supported tokens
const allBalances = await sdk.getBalancesForSwap();

console.log(`Found ${allBalances.length} swap-supported tokens`);

​
Use Cases

// Get balances for source token selection
const assets = await sdk.getBalancesForSwap();

// Filter to tokens with non-zero balance
const availableTokens = assets.filter(asset => 
  parseFloat(asset.balance) > 0
);

// Display in dropdown
const tokenOptions = availableTokens.map(asset => ({
  label: `${asset.symbol} (${asset.balance})`,
  value: asset.symbol,
  icon: asset.icon,
}));

async function canSwap(
  fromToken: string,
  fromChain: number,
  amount: bigint
): Promise<boolean> {
  const assets = await sdk.getBalancesForSwap();
  
  const asset = assets.find(a => a.symbol === fromToken);
  if (!asset) return false;
  
  const chainBalance = asset.breakdown.find(
    b => b.chain.id === fromChain
  );
  if (!chainBalance) return false;
  
  // Convert balance to bigint for comparison
  const balanceRaw = sdk.utils.parseUnits(
    chainBalance.balance,
    chainBalance.decimals
  );
  
  return balanceRaw >= amount;
}

​
Balance Polling

For real-time balance updates, implement polling: 
import { NexusSDK } from '@avail-project/nexus-core';

class BalanceManager {
  private sdk: NexusSDK;
  private pollInterval: NodeJS.Timeout | null = null;
  private subscribers: ((assets: UserAsset[]) => void)[] = [];
  
  constructor(sdk: NexusSDK) {
    this.sdk = sdk;
  }
  
  subscribe(callback: (assets: UserAsset[]) => void) {
    this.subscribers.push(callback);
  }
  
  async startPolling(intervalMs: number = 10000) {
    // Initial fetch
    await this.refresh();
    
    // Poll for updates
    this.pollInterval = setInterval(async () => {
      await this.refresh();
    }, intervalMs);
  }
  
  stopPolling() {
    if (this.pollInterval) {
      clearInterval(this.pollInterval);
      this.pollInterval = null;
    }
  }
  
  private async refresh() {
    try {
      const assets = await this.sdk.getBalancesForBridge();
      this.subscribers.forEach(callback => callback(assets));
    } catch (error) {
      console.error('Failed to refresh balances:', error);
    }
  }
}

// Usage
const balanceManager = new BalanceManager(sdk);

balanceManager.subscribe(assets => {
  console.log('Balances updated:', assets);
  updateUI(assets);
});

// Start polling every 10 seconds
await balanceManager.startPolling(10000);

// Stop polling when done
balanceManager.stopPolling();

​
Error Handling

import { NexusError, ERROR_CODES } from '@avail-project/nexus-core';

try {
  const assets = await sdk.getBalancesForBridge();
} catch (error) {
  if (error instanceof NexusError) {
    switch (error.code) {
      case ERROR_CODES.SDK_NOT_INITIALIZED:
        console.error('SDK not initialized');
        break;
      case ERROR_CODES.WALLET_NOT_CONNECTED:
        console.error('Wallet not connected');
        break;
      case ERROR_CODES.NO_BALANCE_FOR_ADDRESS:
        console.log('No balances found for this address');
        break;
      default:
        console.error('Failed to fetch balances:', error.message);
    }
  }
}

Bridge Operations

Use balances for bridge operations

Swap Operations

Use balances for swap operations