Qtum-light-js NPM

qtum-light-js

qtum-light-js is a JavaScript library for Qtum Light Wallet.

Installation

NPM

npm npm i --save qtum-light-js

Yarn

yarn add qtum-light-js

Usage

Import

import { QtumLightApi } from 'qtum-light-js';

`QtumLightApi` class

QtumLightApi is the single interface to use qtum-light-js.

const qtumLightApi = new QtumLightApi();

Once we create the instance of QtumLightApi, then we can use it to interact with Qtum Light Wallet.

`isQtumLightInstalled` method

isQtumLightInstalled is used to get the installation status of Qtum Light Wallet

const installed = qtumLightApi.isQtumLightInstalled();

`getCurrentAddress` method

getCurrentAddress is used to get current active wallet address, it returns the active wallet address or null if the wallet is locked.

const address = await qtumLightApi.getCurrentAddress();

`queryAccount` method

queryAccount(address) is used to get the account information. It returns a Promise.

const account = await qtumLightApi.queryAccount(address);

`queryTransaction` method

queryTransaction(tx) is used to get the transaction result. It returns a Promise with the transaction information. It throw an error if there is any error like network issue.

const result = await qtumLightApi.queryTransaction(tx);

`queryConfirmation` method

queryConfirmation(tx) is used to get the confirmation. It returns a Promise with the confirmation information. It will keep retrying every period time until the blockchain finish or fail the confirmation. It throw an error if there is any error like network issue.

const result = await qtumLightApi.queryConfirmation(tx, period);

The difference between queryTransaction and queryConfirmation is queryTransaction will return immediately once it retrieve the transaction information. Thus queryConfirmation will keep retrying every period time until the blockchain finish or fail the confirmation.

`DataTypes` property

DataTypes provides a set of data type constants for the input and output of the contract calls. e.g. UINT256, STRING, ADDRESS. We can use them like:

const { UINT256, ADDRESS } = qtumLightApi.DataTypes;

`Contract` method

Contract(address) method takes the address of the contract and returns an object of Contract class. Or returns null if the address is invalid.

const contract = qtumLightApi.Contract('a27225bcb75142b8f90dcf3365055899b7c091fd');

More details can be found in Contract class.

`Contract` class

`constructor` method

the constructor takes an address parameter.

`send` method

send(method, inputData, inputTypes, amount, gasPrice, gasLimit) is used to send a transaction to the smart contract on the blockchain. It is a write operation and needs some gas to process.

method is the name of the method within the smart contract to call.

inputData is the input data e.g. 1, 'abc', true, 'a27225bcb75142b8f90dcf3365055899b7c091fd'.

inputTypes is the input types e.g. UINT256, STRING, BOOL, ADDRESS.

amount is the amount to be sent to the contract.

gasPrice is the gas price to be used for the transaction.

gasLimit is the gas limit to be used for the transaction.

It returns the transaction id in a Promise once the blockchain receives the transaction.

try {
  const result = await contract.send(
    'increment', // method
    [3, 1], // inputData
    [UINT256, UINT256], // inputTypes
    0 // amount
  );

  this.setState({output: result});
} catch (e) {
  this.setState({output: e.message});
}

`call` method

call(method, inputData, inputTypes, outputTypes) is used to call a method within the smart contract on the blockchain. It is a read operation and doesn't need any gas to process.

method is the name of the method within the smart contract to call.

inputData is the input data e.g. 1, 'abc', true, 'a27225bcb75142b8f90dcf3365055899b7c091fd'.

inputTypes is the input types e.g. UINT256, STRING, BOOL, ADDRESS.

outputTypes is the output types e.g. STRING, UINT256, ADDRESS, BOOL.

It returns the data in an array. e.g. 'abc', 1, 'a27225bcb75142b8f90dcf3365055899b7c091fd', true. Or if there is only one data, then only return data without array e.g. 'abc'.

try {
  const result = await contract.call(
    'getCount', // method
    null, // inputData
    null, // inputTypes
    [UINT256, UINT256, ADDRESS] // outputTypes
  );
  this.setState({output: JSON.stringify(result)});
} catch (e) {
  this.setState({output: e.message});
}

`queryTransaction` method

queryTransaction(tx) is same as queryTransaction method in QtumLightApi class.

const result = await contract.queryTransaction(tx);

`queryConfirmation` method

queryConfirmation(tx) is same as queryConfirmation method in QtumLightApi class.

const result = await contract.queryConfirmation(tx, period);

`sendAndConfirm` method

sendAndConfirm(method, inputData, inputTypes, amount, gasPrice, gasLimit, period) is used to send a transaction to the smart contract on the blockchain and wait for the confirmation. It is a write operation and needs some gas to process.

method is the name of the method within the smart contract to call.

inputData is the input data e.g. 1, 'abc', true, 'a27225bcb75142b8f90dcf3365055899b7c091fd'.

inputTypes is the input types e.g. UINT256, STRING, BOOL, ADDRESS.

amount is the amount to be sent to the contract.

gasPrice is the gas price to be used for the transaction.

gasLimit is the gas limit to be used for the transaction.

period is the duration to query the confirmation.

try {
  const result = await contract.sendAndConfirm(
    'increment', // method
    [3, 1], // inputData
    [UINT256, UINT256], // inputTypes
    0 // amount
  );
  this.setState({output: JSON.stringify(result)});
} catch (e) {
  this.setState({output: e.message});
}