Hi all!
I’m now also ready to show my little coinflip Dapp 
So here are two screenshots, the first one showing the admin interface (shown only to the contract-owner) and the second one shows what a regular player sees.
The whole project can be found at https://github.com/Laserbach/CoinFlip_Dapp
The app works well (as far as I can tell 
) but there is one weird issue which I couldn’t figure out. It is a web3 problem:
There seems to be a difference when it comes to promise-handling if using .call() and .send() , take the following examples:
function getBalance() {
contractInstance.methods.getBalance().call().then(function(result){
var amount = web3.utils.fromWei(result, 'ether');
$("#balance").html(amount);
});
}
function getPlayerBalance() {
contractInstance.methods.getPlayerBalance(address).call().then(function(result){
var amount = web3.utils.fromWei(result, 'ether');
$("#playerBalance").html(amount);
});
}
Thse two .call() getter functions work exactly as they should, the smart contract in both cases returns an uint variable (balances in Wei), which I then transform into Ether and display.
Now here we have two .send() setter functions. Those will send funds and again will return me at the end the uint-value of the transfered funds.
function widthdrawFunds() {
contractInstance.methods.withdrawAll().send({from: address}).then(function(result){
var amount = web3.utils.fromWei(result, 'ether');
alert("Balance withdrawn!")
console.log(amount);
getBalance();
})
}
function widthdrawWinnings() {
contractInstance.methods.withdrawPlayer().send({from: address}).then(function(result){
var amount = web3.utils.fromWei(result, 'ether');
alert("Here is your reward!")
console.log(amount);
getPlayerBalance();
})
}
Now the weird thing with those .send() functions is, that web3.utils.fromWei will throw the following error:
I know, the problem isnt really dramatic and I dont rely on the return-value which is delivered via the promise since I just wanted to use it for logging / testing. Also the smart-contract transaction actually goes through, so this error just breaks the function in the frontend (the getBalance() function wont be executed which leads to an outdated frontend page).
Anyways I would be interested to know what the actual problem here is. I tried many different things like .toFixed() or .toString() as it was suggested in some forums but nothing would fix this issue. And whats annoying the most is the fact that in the .call() functions it perfectly works this way, using the same return values and promise handling… 
Does anybody here have an idea on how to fix it?
Also @gabba I would be glad if you could roast my code 
Best - Lars
. My app now supports switching between networks and accounts smoothly (no reload).
