Intracting with dapp using frontend truffle petbox

External question — Ethereum Stack Exchange Author: md venkatesh Original post: https://ethereum.stackexchange.com/questions/60610 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. App = { web3Provider: null, contracts: {}, account: '0x0', init: function() { // Load pets. return App.initWeb3(); }, initWeb3: function() { if (typeof web3 !== 'undefined') { // If a web3 instance is already provided by Meta Mask. App.web3Provider = web3.currentProvider; web3 = new Web3(web3.currentProvider); } else { // Specify default instance if no web3 instance provided App.web3Provider = new Web3.providers.HttpProvider('http://localhost:7545'); web3 = new Web3(App.web3Provider); } return App.initContract(); }, initContract: function() { $.getJSON("adding.json", function(addingdappfrontend) { App.contracts.Add = TruffleContract(addingdappfrontend); // we have to set provideer App.contracts.Add.setProvider(App.web3Provider); return App.render(); }); }, render : function(){ var addingInstance; // loading data web3.eth.getCoinbase(function(err, account) { if (err === null) { App.account = account; $("#accountAddress").html("Your Account: " + account); } }); // Load contract data $("#add").click(function(){ App.contracts.Add .deployed().then(function(i){ app = i return app.add($("#fvalue").val() , $("#svalue").val()); }).then(function(j){ $("#total").val(j.total()); }); }); } }; $(function() { $(window).load(function() { App.init(); }); }); The following code is my app.js code for the ui of my block chain <!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1"> <!-- The above 3 meta tags *must* come first in the head; any other head content must come *after* these tags --> <title>Adding and Subracting Twonumbers </title> <!-- Bootstrap --> <link href="css/bootstrap.min.css" rel="stylesheet"> </head> <body> <div class="container"> <div class="row"> <div class="col-xs-12 col-sm-8 col-sm-push-2"> <h1 class="text-center">adding Two Numbers</h1> <hr/> <br/> Firstvalue</br> <input type="number" name="fvalue" id = "fvalue" value=""></br> second Value</br> <input type = "number" name = "svalue" id = "svalue" value = ""></br> Total</br> <input type = "number" name= "total" id = "total" value = ""> </br> </br><button name="add" id="add">Add</button> </div> </div> <p id="accountAddress" class="text-center"></p> </div> <!-- jQuery (necessary for Bootstrap's JavaScript plugins) --> <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script> <!-- Include all compiled plugins (below), or include individual files as needed --> <script src="js/bootstrap.min.js"></script> <script src="js/web3.min.js"></script> <script src="js/truffle-contract.js"></script> <script src="js/app.js"></script> </body> </html> I have written my index.html code i want to link to my backend solidity code and call my add function and deploy the total in total box provided in my index.html code pragma solidity ^0.4.23; contract adding{ uint256 public total; function add(uint256 val1,uint256 val2) public returns(uint256){ total = val1+val2; return total; } } The above code is giving me the following error Failed to load resource: net::ERR_CONNECTION_REFUSED app.js:54 14 browser-sync-client.js?v=2.26.3:9 GET http://localhost:3000/browser-sync/socket.io/?EIO=3&transport=polling&t=MPxk1Re net::ERR_CONNECTION_REFUSED i.create @ browser-sync-client.js?v=2.26.3:9 i @ browser-sync-client.js?v=2.26.3:9 o.request @ browser-sync-client.js?v=2.26.3:9 o.doPoll @ browser-sync-client.js?v=2.26.3:9 n.poll @ browser-sync-client.js?v=2.26.3:9 n.doOpen @ browser-sync-client.js?v=2.26.3:9 n.open @ browser-sync-client.js?v=2.26.3:9 n.open @ browser-sync-client.js?v=2.26.3:9 n @ browser-sync-client.js?v=2.26.3:9 n @ browser-sync-client.js?v=2.26.3:9 n.open.n.connect @ browser-sync-client.js?v=2.26.3:9 (anonymous) @ browser-sync-client.js?v=2.26.3:9 browser-sync-client.js?v=2.26.3:9 GET http://localhost:3000/browser-sync/socket.io/?EIO=3&transport=polling&t=MPxk2fv net::ERR_CONNECTION_REFUSE

External answer — Ethereum Stack Exchange Author: Aquila Original post: https://ethereum.stackexchange.com/a/60635 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. There are lots of code above, but not enough info to help you First suggestion, make sure that adding.json is accessible After solving of current issue, you may face to: $("#add").click(function() { App.contracts.Add.deployed().then(function(i) { return i.add($("#fvalue").val(), $("#svalue").val()); }).then(function(j) { $("#total").val(j); }); });

External answer — Ethereum Stack Exchange Author: md venkatesh Original post: https://ethereum.stackexchange.com/a/60657 License: CC BY-SA 4.0 — https://creativecommons.org/licenses/by-sa/4.0/ Adaptation: HTML converted to plain text; contact email addresses removed. I have changed my function to pure function it worked fine pragma solidity ^0.4.23; contract adding{ function add(uint256 val1,uint256 val2) public pure returns(uint256){ //uint256 public total; uint256 total = val1+val2; return total; } } Unit test is going wrong refer to the following link for explanation