Ethereum, tokens & smart contracts.

Notes on getting started Part 2. web3.js

So once you have a wallet, are on a test net and have some ether ( read part 1. if any of this is not clear ) where to go next ?

Let’s start coding, web3.js and Solidity seem to be the entry points for interacting with the blockchain programmatically and making contracts & tokens, web3.js I think is a nice prequel to working with solidity, so let’s check it out first:

web3.js :

Docs

web3.js is the javascript API for interacting with the Ethereum blockchain, the easiest way to explain it is through a couple of basic examples. A cool and simple way to test some basic commands is via the parity/web3 console:

Let’s start by requesting my balance:

web3.eth.getBalance("0x001301AD1556fD419Cf8970B174fE9AF34267eB8")
// 3000000000000000000

Importantly the balance is displayed in wei, not ether, but conveniently there is a function in the api that converts to ether (or other denominations)

web3.fromWei(web3.eth.getBalance("0x001301AD1556fD419Cf8970B174fE9AF34267eB8"), 'ether')
// 3

Speaking of denominations, here they are in ether:

| wei                   | 0.000000000000000001 
| kwei - ada            | 0.000000000000001    
| mwei - babbage        | 0.000000000001       
| gwei -shannon         | 0.000000001          
| szabo                 | 0.000001             
| finney                | 0.001                
| ether                 | 1                    
| kether-grand-einstein | 1000                 
| mether                | 1,000,000            
| gether                | 1,000,000,000        
| tether                | 1,000,000,000,000    

And in wei:

| wei                   | 1                                         
| kwei - ada            | 1,000                                     
| mwei - babbage        | 1,000,000                                 
| gwei -shannon…