Requesting Information from the Ethereum Provider
Again, we need our server file that delivers the website using Express.
You can find the code here:
var express = require("express");
var path = require("path");
var app = express();
app.listen(3000);
console.log("Listening to Port 3000");
app.get('/', function(req, res){
res.sendFile(path.join(__dirname, './','providerAPI_browser01.html')); //Adjust path according to your project
});The provider API works as follows:
ethereum.request({
method: 'METHOD NAME,
params})
.then(function(result){
})
.catch(function(error) => {
});
The name of the RPC method and its parameters are submitted.
Parameters are typically provided as array.
[‘value 1’, ‘value 2’]or as an object
[{
param1: 'value 1',
param2: 'value 2',
param3: 'value3'
}]
The function returns a promise which is caught with then().
If an error occurs, we can catch it with catch().
You can find the code sample here:
<!DOCTYPE html>
<html>
<head>
<script src='web3.min.js'>
</script>
<script>
window.addEventListener("load", (event)=>{
if(window.ethereum){
ethereum.request({method: 'eth_requestAccounts'}).then(function(accounts){
console.log(accounts);
document.getElementById("accounts").innerHTML = accounts;
// Or by using our conveniance library web3.js
window.web3 = new Web3(window.ethereum);
web3.eth.getBlockNumber().then(function(blknr){
console.log(blknr);
document.getElementById("blockNumber_Web3").innerHTML = blknr;
})
})
}else{
return false
}
})
</script>
</head>
<body>
<h1>My First DApp</h1>
<div>Accounts </div>
<div id = "accounts"></div>
<div>Blocknumber by web3.js: </div>
<div id = "blockNumber_Web3"></div>
</body>
</html>Don’t forget to change the file name in our JavaScript file.
