All transactions are securely signed on your end, so your private key remains with you and never comes to us over API. We do not hold your crypto at any point: :closed_lock_with_key: Your keys, Your crypto. Our APIs are a one-stop-shop for you to make the enquiries and conduct the transactions as you want.

Client-Side Security Essentials

Certificate transparency

CT makes it easier to detect and prevent digital certificate fraud, thereby improving the security of internet connections.

In addition to implementing certificate transparency measures on our end, we highly recommend users to also consider implementing these measures for added security benefits.

Private Key

A user's private key is stored securely in a digital wallet, and should never be shared with anyone as it provides full access and control over their digital assets.

It is highly recommended that users take necessary precautions to ensure the safety and confidentiality of their private keys, as we do not possess any access or control over them.

Additional Security Precautions

• It is important for the user to safeguard both their data and workstation from potential risks such as spoofing, tampering, and other related threats.
• It is important for the end user to connect to a secure network and ensure that they use only TLS 1.2 or a newer version for enhanced security to safeguard them from any kind of threats and attacks.

Installation

To install, clone the repository from git directly.

git clone https://github.com/expand-network/sdk-nodejs.git

Or, use the following npm package.

npm i expand-network

Usage

You can get your API key by visiting our website or by clicking here

Chain functions

Sample code: Send one Wei from one public address to another public address. You need to use your private key to sign the transaction. The return value is the transaction hash (res).

const { Wallet, prepareTransaction } = require('expand-network');

async function main(){
    const wallet = new Wallet({ privateKey: 'YOUR_PRIVATE_KEY', xApiKey: 'YOUR_API_KEY' });

    // Signing transaction
    const signedTx = await wallet.signTransaction({
        from: 'PUBLIC_ADDRESS',
        to: 'PUBLIC_ADDRESS',
        value: '1',
        chainId: '1',
        gas: '50000',
    }); 

    //Sending transaction
    const tx = await wallet.sendTransaction(signedTx);
    console.log("Transaction Pending....", tx.data);
}
main()

Fungible functions approve

Sample code: Approve 5 DAI (token ending in d0F),In this example, the "from" is the user address (ending in 006) and "to" is protocol address (ending in 056), so 5 DAI is approved from user address on the protocol address. User need to use private key to sign the transaction.

const { Wallet, prepareTransaction } = require('expand-network');

async function approve() {
    const wallet = new Wallet({ privateKey: 'YOUR_PRIVATE_KEY', xApiKey: 'YOUR_API_KEY' });
    
    // Preparing transaction
    const preparedTx = await prepareTransaction('https://api.expand.network/fungibletoken/approve', {
      from: 'PUBLIC_ADDRESS',
      to: 'PUBLIC_ADDRESS', // The spender's or contract's or router's address that needs to be approved
      tokenAddress:"0x6B175474E89094C44Da98b954EedeAC495271d0F", 
      amount: "5000000000000000000",
      gas: '100000',
      chainId:"1"
      xApiKey: "YOUR_API_KEY"
    });

    // Signing transaction
    const signedTx = await wallet.signTransaction(preparedTx); 

    //Sending transaction
    const tx = await wallet.sendTransaction(signedTx);
    console.log("Transaction Pending....", tx.data);
}

approve();

Dex functions swap

Sample code: Swap 5 DAI (token ending in d0F) with WETH (token ending in Cc2). In this example, the "to" and "from" are the same (ending in 006), so the swapped tokens will come back into the same address. Again, you need to use your private key to sign the transaction.

const { Wallet, prepareTransaction } = require('expand-network');

async function swap() {
  const wallet = new Wallet({ privateKey: 'YOUR_PRIVATE_KEY', xApiKey: 'YOUR_API_KEY' });
  
  // Preparing transaction
  const preparedTx = await prepareTransaction('https://api.expand.network/dex/swap', {
    amountIn: '5000000000000000000',
    amountOutMin: '0',
    path: ['0x6B175474E89094C44Da98b954EedeAC495271d0F','0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2'], // DAI and WETH contract addresses
    to: 'PUBLIC_ADDRESS',
    deadline: '1693143453', // Epoch Unix timestamp
    from: 'PUBLIC_ADDRESS',
    gas: '229880',
    xApiKey : 'YOUR_API_KEY',
    chainId:"1"
  });

  // Signing transaction
  const signedTx = await wallet.signTransaction(preparedTx); 

  //Sending transaction
  const tx = await wallet.sendTransaction(signedTx);
  console.log("Transaction Pending....", tx.data);
}
swap();

Expand now supports Versioned transactions on Solana

Versioned transaction

Versioned Transactions are the new transaction format that allows for additional functionality in the Solana runtime, including Address Lookup Tables.

The Solana runtime supports two transaction versions:

• legacy - older transaction format with no additional benefit
• 0 - added support for Address Lookup Tables

*(0 is known as versioned transaction)

Now using expand users can leverage Versioned Transactions to pack richer instruction sets into a single transaction and use lookup tables.

Examples

Get balance

Sample code: get balances from different chains: Ethereum, BSC and Solana.

//Setting API-KEY for axios header 
axios.defaults.headers['X-API-KEY'] = "YOUR_API_KEY";
 // Fetching balance from Ethereum
config.params = {
    address: publicAddressEvm
}
response = await axios.get(baseUrl + '/chain/getbalance/', config);
balance = response.data.data.balance / 10**18; // Divide by 10 to the power decimals of the asset (18 for ETH)
console.log (`${publicAddressEvm} balance on ethereum chain is ${balance}`);
// Fetching balance from Binance Smart Chain 
config.params = {
    chainId: '56',
    address: publicAddressBsc
}
response = await axios.get(baseUrl + '/chain/getbalance/', config);
balance = response.data.data.balance / 10**18;
console.log (`${publicAddressBsc} balance on binance smart chain is ${balance}`);
// Fetching balance from Solana 
config.params = {
    chainSymbol: 'SOL',
    address: publicAddressSolana
}
response = await axios.get(baseUrl + '/chain/getbalance/', config);
balance = response.data.data.balance / 10**9;
console.log (`${publicAddressSolana} balance on solana chain is ${balance}`);

Swap with best price

Sample Code: For the swap pair DAI <> WETH, find the best price on three different DEX protocols: Uniswap v2, v3, and Sushiswap. Whichever DEX has the best price, swap the DAI with WETH on that particular DEX.

const { Wallet, prepareTransaction } = require('expand-network');

const getPrice = async(dexId) => {
  config.params = {
      dexId: dexId,
      path: '0x6B175474E89094C44Da98b954EedeAC495271d0F' + ',' + '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2',
      amountIn: amount
  }
  const response = await axios.get(baseUrl + '/dex/getprice/', config);
  prices[dexId] = response.data.amountsOut[1];
}

const swap = async(dexId) => {
  const wallet = new Wallet({ privateKey: 'YOUR_PRIVATE_KEY', xApiKey: 'YOUR_API_KEY' });

  const preparedTx = await prepareTransaction(baseUrl + '/dex/swap', {
    dexId,
    amountIn: amount,
    amountOutMin: '0',
    path: [ '0x6B175474E89094C44Da98b954EedeAC495271d0F', '0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2' ],
    to: 'PUBLIC_ADDRESS',
    deadline: Date.now() + 60*60*20,
    from: 'PUBLIC_ADDRESS',
    gas: '229880',
    xApiKey : 'YOUR_API_KEY'
  });

  // Signing transaction
  const signedTx = await wallet.signTransaction(preparedTx); 

  //Sending transaction
  const tx = await wallet.sendTransaction(signedTx);
  console.log("Transaction Pending....", tx.data);
}

const bestBuy = async() => {
  // Fetching price from Uniswap V2
  await getPrice('1000');
  // Fetching price from Sushiswap
  await getPrice('1100');
  // Fetching price from Uniswap V3
  await getPrice('1300');
  var max = 0;
  var maxDexId = 0;
  for ( var dexId in prices ){
      if ( Number(prices[dexId]) > max ) {
          max = prices[dexId];
          maxDexId = dexId;
      }
  }
  
  console.log(`${maxDexId} gives the best swap price of ${max}`);
  // Time to swap the tokens
  swap(maxDexId);
}
bestBuy();

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