FIXED !! I did some more digging and solved the problem. For some reason the server was not updating the contract changes. Easy fix:
What a relief 
Thanks for the help though!
@filip Thanks for your great lessons so far. I’ve got my first phase to work. UI could use some polishing but that can wait for later. I was wondering where can I find documentation and examples on how to handle errors or exceptions from the contract in Javascript.
hi @dan-i
Please see below the main.js code
contractFunded is the event
var web3 = new Web3(Web3.givenProvider);
var contractInstance;
$(document).ready(function(){
window.ethereum.enable().then(function(accounts){
contractInstance = new web3.eth.Contract(abi, web3.utils.toChecksumAddress("0xBd8Faa10595d86c39a89AD0e21041ee0E0cF0202"), {from : accounts[0]});
console.log(contractInstance);
console.log(`Use Contract address: ${contractInstance._address}`)
});
$("#flip_button").click(flipCoin);
$("#get_balance").click(fetchAndDisplay);
$("#fund_contract_button").click(fundContract);
$("#withdraw_funds").click(withdrawAll);
});
function flipCoin(){
var bet = $("#bet_input").val();
var config = {
value: web3.utils.toWei(bet,"ether")
}
contractInstance.methods.flipCoin().send(config)
.on("transactionHash", function(hash){
console.log(hash);
})
.on("confirmation", function(confirmationNr){
console.log(confirmationNr);
})
.on("receipt", function(receipt){
console.log(receipt);
if(receipt.events.betPlaced.returnValues[2] === false){
alert("You lost " + bet + " Ether!");
}
else if(receipt.events.betPlaced.returnValues[2] === true){
alert("You won " + bet + " Ether!");
}
})
};
function fetchAndDisplay(){
contractInstance.methods.getBalance().call().then(function(res){
$("#jackpot_output").text("The Contract has : " + web3.utils.fromWei(res[1], "ether") + "Ether");
})
};
function fundContract(){
var fund = $("#fund_contract").val();
var config = {
value : web3.utils.toWei(fund, "ether")
}
contractInstance.methods.fundContract().send(config)
.on("transactionHash", function(hash){
console.log(hash);
})
.on("confirmation", function(confirmationNr){
console.log(confirmationNr);
})
.on("receipt", function(receipt){
console.log(receipt);
receipt.events.contractFunded(function(error, result){
alert("The Contract has now been funded by :" + result.returnValues.amount(web3.utils.fromWei(amount, "ether")) + "Ether");
})
})
};
function withdrawAll(){
contractInstance.methods.withdrawAll().send();
};
also, see below the solidity code:
pragma solidity 0.5.12;
contract Coinflip {
address public contractOwner;
constructor() public {
contractOwner = msg.sender;
}
modifier onlyOwner() {
require(msg.sender == contractOwner, "You are not the owner");
_;
}
uint public contractBalance;
address public contractAddress;
modifier costs(uint cost) {
require(msg.value >= cost, "Minimum amount >= 0.01 ether");
_;
}
event betPlaced(address user, uint bet, bool);
event contractFunded(address contractOwner, uint amount);
//Flip the Coin and check whether user won or lost;
function flipCoin() public payable costs(0.01 ether) returns(bool success) {
require(address(this).balance >= msg.value, "The contract doesnt have enough balance to play right now. Come Back later");
if (now % 2 == 0) {
contractBalance += msg.value;
success = false;
}
else if (now % 2 == 1){
contractBalance -= msg.value;
msg.sender.transfer(msg.value * 2);
success = true;
}
//event to be emitted
emit betPlaced(msg.sender, msg.value, success);
return success;
}
function getBalance() public view returns(address, uint, uint) {
return(address(this), address(this).balance, contractBalance);
}
// withdraw all funds possible only though contractOwner address;
function withdrawAll() public onlyOwner returns(uint){
msg.sender.transfer(address(this).balance);
assert(address(this).balance == 0);
return address(this).balance;
}
function fundContract() public payable onlyOwner returns(uint) {
require(msg.value != 0);
emit contractFunded(msg.sender, msg.value);
return msg.value;
}
}
What am I doing wrong here ??
thanks and Regards
su.kal Crypto
Hey @Su.kal.Crypto
I tried your code few days ago and I was getting the pop up with the result, but the goal is to catch events.
Because you told me that you followed the faq, can you please share the code? I want to see where you doing errors and correct them 
Regards,
Dani
Hey @Vivek20
Can you give an example of the kind of errors you are getting?
Also in JS usually you handle errors by using catch statements, but really I would need to see the errors to be more precise.
Waiting for you code I wish you a nice day,
Dani
Thanks Dani, perhaps I’m just over complicating things. I’ll post some code later.
If you need help I am here
Finally got finished up with part 1! 
This was my first time using bootstrap so I had to learn how to use the CSS with that which was a great learning opportunity. I do still need to add the error handlers and tests but will sharpen that up after part 2. Thank you @dan-i for the help on this first part. Hopefully it came out well.
Page Responsiveness
https://drive.google.com/file/d/1IJQPx8aTP-z7suPxwcKittvkEOYvVh3L/view
Contract Functionality
https://drive.google.com/file/d/1Q1smZffGkp-CB1iZFzDWB_TPfz0vfz0A/view
Hi @dan-i
My code is below 
https://github.com/Suveett/coinFlip-Dapp.git
It’s the same since last 9 days wherein i committed some changes.
The problem is in this line below
receipt.events.contractFunded(function(error, result){
alert("The Contract has now been funded by :" + result.returnValues.amount(web3.utils.fromWei(amount, "ether")) + "Ether");
})
I am asking specifically for an Alert, but there is no pop up on my Window:
Please let me know by having a look at my code. Probably I haven’t wrapped my head around catching events properly, although I feel sensibly that I am doing the right things ( right lines of code)
So let me know.
Also, today while reloading my localhost:8000, I see that Metamask has stopped injecting web3 ?
can you tell me the changes in code so as to get around this 
Thanks and Regards
su.kal Crypto
Hey @Su.kal.Crypto
I checked your main.js last time and I tried to play with your contract too this is why I was suggesting to check the faq, you should not use the receipt but the contractnstance
We created a step by step procedure that should clear all the doubts: FAQ - How to listen for events
This is an example of how it suppose to look like:
instance.events.newNumber(function (error,result){
console.log('Here it is' + ' ' + result.returnValues._newNumber)
})
You can also use contractInstance.once, check this out, I wrote a clean and easy code to showcase: https://github.com/dani69654/CoinFlip/blob/master/client/main.js
Also the web3 docs explains it really good and gives you lots of examples:
Give it a try and keep me posted.
Regards,
Dani
Thanks @dan-i 
Will check and try out the entire code and get back to you, and also understand where I am going wrong ans then implement corrections in my code …
Su.kal Crypto
Got an Error with the following Code when i want to get my balance:
window.ethereum.enable().then(function (accounts) {
users = accounts;
contractInstance = new web3.eth.Contract(abi, contract, { from: accounts[0] });
console.log(contractInstance.events);
contractInstance.events.contractFunded((err, ev) => {
$("#result").html("Funded");
console.log('Funded', ev)
});
contractInstance.events.wonFlip((err, ev) => {
$("#result").html("Won");
console.log('Won', ev)
});
contractInstance.events.loseFlip((err, ev) => {
$("#result").html("Lost");
console.log('Lost', ev)
});
$("#balance").click(() => {
contractInstance.methods.getBalance().call().then(function (res) {
$("#contractBalance").html(web3.utils.fromWei(res[1], "ether") + "Ether");
})
function getBalance() public view returns (uint256) {
return address(this).balance;
}
Uncaught (in promise) Error: Internal JSON-RPC error.
{
"message": "VM Exception while processing transaction: invalid opcode",
"code": -32000,
"data": {
"0x5fbd1fccf1cfc4166a4eb02aaff649068f8d28d827491cc1791c5a7f2dc37a18": {
"error": "invalid opcode",
"program_counter": 320,
"return": "0x"
},
"stack": "RuntimeError: VM Exception while processing transaction: invalid opcode\n at Function.RuntimeError.fromResults (/Applications/Ganache.app/Contents/Resources/static/node/node_modules/ganache-core/lib/utils/runtimeerror.js:94:13)\n at /Applications/Ganache.app/Contents/Resources/static/node/node_modules/ganache-core/lib/blockchain_double.js:568:26",
"name": "RuntimeError"
}
}```
Could anyone help? i can deposit to the smart contract. but when i try to check the balance it crashes always. any idea why?Hi guys,
I’m running into an issue when I redeploy my contract with an added function. I’m not able to see the added function when I console.log the instance, even though I updated my abi and contract address. Can someone help me with this? It’s really frustrating and doesn’t make any sense to me why this is happening.
Hi @niore
Can you just console.log(res) and post the result?
$("#balance").click(() => {
contractInstance.methods.getBalance().call().then(function (res) {
console.log(res)
})
Hi @KaiStryker
Please post your abi and your smart contract.
You either did not update your ABI correctly, or your python server is not updating the changes.
Thanks,
Dani
Hey Dani,
I fixed it, thanks. Turns out all I needed to do was clear the cache in my browser.
Hi guys,
I have to do the project 1 after I have finished C++ and javascript, I got confused a bit when I was checking Github, I got so much random information about Github not organized wihtout reaching what I need for my project, probably I’m going to do a grocery list with javascript.
Do I have to write on atom first then create a connection? anybody can help me if you a good tutorial about it?
Thanks in advance
New issue:
I am trying to call an event and log the results on the Frontend but every time I try to do this the site doesn’t respond with the results. Here is the code:
.then(contractInstance.getPastEvents(‘Results’,
{
fromBlock:‘latest’
},function(error, events){
console.log(events); })).then(function(events){
$("#get_results_output").text(events._results);
When I try $("#get_results_output").text(events), that works but of course that only returns the text object on the page.
P.S.
What I’m trying to return is a string that says either “You Won!” or “Sorry Try Again!”
Update: I figured it out. The solution is:
.then(contractInstance.getPastEvents(‘Results’,
{
fromBlock:‘latest’
},function(error, _events){
console.log(_events); })).then(function(_events){
$("#get_results_output").text(_events.events.Results.returnValues[’_results’]);
});
When I run this however, in the console.log the event is from the last transaction and not the current one. How do I fix this?
