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API Architecture

The library follows common api architecture throughout and the APIs are divided into two types -

  1. Read API
  2. Write API

Read API

Read APIs does not publish anything on blockchain, so it does not consume any gas. Example of read APIs are - getBalance, isWithdrawExited etc.

Let's see an example of read API -

const erc20 = posClient.erc20('<token address>');
const balance = await erc20.getBalance('<user address>')

read APIs are very simple and returns result directly.

Write API

Write APIs publish some data on the blockchain, so it consumes gas. Example of write APIs are - approve, deposit etc.

When you are calling a write API - you need two data from the result.

  1. TransactionHash
  2. TransactionReceipt

Let's see an example of write API and get the transactionhash and receipt -

const erc20 = posClient.erc20('<token address>');

// send the transaction
const result = await erc20.approve(10);

// get transaction hash

const txHash = await result.getTransactionHash();

// get receipt

const receipt = await result.getReceipt();

Transaction option

There are some configurable options that are available for all API's. These configurations can be passed in parameters.

Available configurations are -

  • from?: string | number - The address transactions should be made from.
  • to?: string - The address transactions should be made to.
  • value?: number | string | BN - The value transferred for the transaction in wei.
  • gasLimit?: number | string - The maximum gas provided for a transaction (gas limit).
  • gasPrice?: number | string | BN - The gas price in wei to use for transactions.
  • data?: string - The byte code of the contract.
  • nonce?: number;
  • chainId?: number;
  • chain?: string;
  • hardfork?: string;
  • returnTransaction?: boolean - making it true will return the transaction object which can be used to send transaction manually.

Let's see an example by configuring the gasPrice

const erc20RootToken = posClient.erc20(<root token address>,true);

// approve 100 amount
const approveResult = await erc20Token.approve(100, {
gasPrice: '4000000000',

const txHash = await approveResult.getTransactionHash();

const txReceipt = await approveResult.getReceipt();