gxbjs

GXBJS (gxbjs)

Pure JavaScript GXChain library for node.js and browsers. Can be used to construct, sign and broadcast transactions in JavaScript, and to easily obtain data from the blockchain via public apis.

Most of this code was written by jcalfee, my work was mostly just repackaging to a discrete npm package.

Setup

This library can be obtained through npm:

npm install gxbjs

Usage

Three sub-libraries are included: ECC, Chain and Serializer. Generally only the ECC and Chain libraries need to be used directly.

Chain

This library provides utility functions to handle blockchain state as well as a login class that can be used for simple login functionality using a specific key seed.

Login

The login class uses the following format for keys:

keySeed = accountName + role + password

Using this seed, private keys are generated for either the default roles active, owner, memo, or as specified. A minimum password length of 12 characters is enforced, but an even longer password is recommended. Three methods are provided:

generateKeys(account, password, [roles])
checkKeys(account, password, auths)
signTransaction(tr)

The auths object should contain the auth arrays from the account object. An example is this:

{
    active: [
        ["GPH5Abm5dCdy3hJ1C5ckXkqUH2Me7dXqi9Y7yjn9ACaiSJ9h8r8mL", 1]
    ]
}

If checkKeys is successful, you can use signTransaction to sign a TransactionBuilder transaction using the private keys for that account.

State container

The Chain library contains a complete state container called the ChainStore. The ChainStore will automatically configure the set_subscribe_callback and handle any incoming state changes appropriately. It uses Immutable.js for storing the state, so all objects are return as immutable objects. It has its own subscribe method that can be used to register a callback that will be called whenever a state change happens.

The ChainStore has several useful methods to retrieve, among other things, objects, assets and accounts using either object ids or asset/account names. These methods are synchronous and will return undefined to indicate fetching in progress, and null to indicate that the object does not exist.

import {Apis} from "gxbjs-ws";
var {ChainStore} = require("gxbjs");

Apis.instance("wss://node.gxb.io", true).init_promise.then((res) => {
    console.log("connected to:", res[0].network);
    ChainStore.init().then(() => {
        ChainStore.subscribe(updateState);
    });
});

let dynamicGlobal = null;
function updateState(object) {
    dynamicGlobal = ChainStore.getObject("2.1.0");
    console.log("ChainStore object update\n", dynamicGlobal ? dynamicGlobal.toJS() : dynamicGlobal);
}

ECC

The ECC library contains all the crypto functions for private and public keys as well as transaction creation/signing.

Private keys

As a quick example, here's how to generate a new private key from a seed (a brainkey for example):

var {PrivateKey, key} = require("gxbjs");

let seed = "THIS IS A TERRIBLE BRAINKEY SEED WORD SEQUENCE";
let pkey = PrivateKey.fromSeed( key.normalize_brainKey(seed) );

console.log("\nPrivate key:", pkey.toWif());
console.log("Public key :", pkey.toPublicKey().toString(), "\n");

Transactions

TODO transaction signing example

ESDoc (beta)

npm i -g esdoc esdoc-es7-plugin
esdoc -c ./esdoc.json
open out/esdoc/index.html