promisify-smart-contract-func

A simple npm package to help you Promisify your Web3 calls that requires a callback

What is this for

When you try to do function calls (such as from Metamask) such as

var balance = web3.eth.getBalance(yourEthAddress);

You will get the following error

Uncaught Error: The MetaMask Web3 object does not support synchronous methods like eth_getBalance without a callback parameter.

This package allows you to get around the callback requirements by wrapping your functions into a Promise.

This allows you to avoid what Javascript developers like to call as callback hell

Installation

Run

npm install --save promisify-smart-contract-func

Example usage

import promisifySmartContractFunc from 'promisify-smart-contract-func';

Using With Parameters

With promisifySmartContractFunc

import promisifySmartContractFunc from 'promisify-smart-contract-func';
.
.
.
try {
  const balance = await promisifySmartContractFunc(
    web3.eth.getBalance, // Function
    address // Parameters
  );
  const approveTransactionHash = await promisifySmartContractFunc(
    token.approve, // Function
    contractAddress, amount // Parameters
  );
  if (approveTransactionHash) {
    console.log(balance);
    console.log(approveTransactionHash);
    // Do something
  }
} catch (error) {
  console.error(error);
  throw(error);
}

Without promisifySmartContractFunc

web3.eth.getBalance(address, (error1, balance) => {
  contract.tokensDeposited(contractAddress, (error2, approveTransactionHash) => {
    if (approveTransactionHash) {
      console.log(balance);
      console.log(approveTransactionHash);
      // Do something ...
    }
    if (error2) {
      console.error(error2);
      throw(error2);
    }
  });
  if (error1) {
    // Do something ...
    console.error(error1);
    throw(error1);
  }
});

Using Without Parameters

With promisifySmartContractFunc

import promisifySmartContractFunc from 'promisify-smart-contract-func';
.
.
.
try {
  const tokenDeposited = await promisifySmartContractFunc(contract.tokensDeposited);
  console.log(tokenDeposited)
} catch (error) {
  console.error(error);
  throw(error);
}

Without promisifySmartContractFunc

contract.tokensDeposited((error, value) => {
  if (value) {
    // Do something ...
  }
  if (error) {
    // Do something ...
  }
});