web3js-notes
These are for quick reference. For hands on practice, checkout cryptozombies tutorial
For Web3js official Documentation
What is Web3.js?
Remember, the Ethereum network is made up of nodes, with each containing a copy of the blockchain. When you want to call a function on a smart contract, you need to query one of these nodes and tell it:
The address of the smart contract The function you want to call, and The variables you want to pass to that function.
Ethereum nodes only speak a language called JSON-RPC, which isn't very human-readable. A query to tell the node you want to call a function on a contract looks something like this:
// Yeah... Good luck writing all your function calls this way!
// Scroll right ==>
{"jsonrpc":"2.0","method":"eth_sendTransaction","params":[{"from":"0xb60e8dd61c5d32be8058bb8eb970870f07233155","to":"0xd46e8dd67c5d32be8058bb8eb970870f07244567","gas":"0x76c0","gasPrice":"0x9184e72a000","value":"0x9184e72a","data":"0xd46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675"}],"id":1}Luckily, Web3.js hides these nasty queries below the surface, so you only need to interact with a convenient and easily readable JavaScript interface.