NOTE: This is a draft in progress, so that I can get some feedback from early reviewers. It is not yet ready for learning.
[[REVISE TO BE ABOUT MULTIPLE LANGUAGES]] [[GIVE EXTENSIVE DETAILS FOR NODE, AND LIST SOME OTHERS]]
Here's the master list: many other options
Accessing the bitcoind doesn't require curl. All you need is simple RPC functionality. That's what's provided by BCRPC by kallewoof of Digital Garage.
BCRPC is built on node.js. Thus, you'll first need to install the node.js and npm (node package manager) packages for your system.
If you're using a Ubuntu machine, you can run the following commands to get a new version of node.js (as opposed to the horribly out-of-date version in the Ubuntu package system).
curl -sL https://deb.nodesource.com/setup_8.x | sudo -E bash -
sudo apt-get install -y nodejs
sudo apt-get install mocha -g
Create a new node.js project and install BCRPC via NPM.
$ mkdir myproject
$ cd myproject
$ npm init
[...]
$ npm install --save bcrpc
To test the BCRPC package, you must first set environmental variables for your rpcuser and rpcpassword. As noted in §12.1: Accessing Bitcoind with Curl, these come from ~/.bitcoin/bitcoin.conf.
$ export BITCOIND_USER=bitcoinrpc
$ export BITCOIND_PASS=d8340efbcd34e312044c8431c59c792c
WARNING: Obviously, you'd never put set your password in an environmental variable in a production environment.
You can now verify everything is working correctly:
$ npm test
> [email protected] test /home/user1/bcrpc-master
> mocha tests.js
BitcoinD
✓ is running
bcrpc
✓ can get info
2 passing (36ms)
Congratulations, you now have a Bitcoin-ready RPC wrapper for node.js.