handle endpoint updating and errors

assets/js/universal-dapp.js

@@ -22,7 +22,7 @@ function UniversalDApp (contracts, options) {
     } else {
         var host = options.host || "localhost";
         var port = options.port || "8545";
-        var rpc_url = options.web3endpoint || ('http://' + host + ':' + port);
+        var rpc_url = options.getWeb3endpoint ? options.getWeb3endpoint() : ('http://' + host + ':' + port);
         web3.setProvider( new web3.providers.HttpProvider( rpc_url ) );
     }
 
@@ -296,7 +296,8 @@ UniversalDApp.prototype.getCallButton = function(args) {
 
                 }
                 tryTillResponse( result, function(err, result) {
-                    if (isConstructor) {
+                    if (err) replaceOutput($result, $('<span/>').text(err).addClass('error'));
+                    else if (isConstructor) {
                         $result.html('');
                         args.appendFunctions(result.contractAddress);
                     } else {

index.html

@@ -234,7 +234,11 @@
 
 			$vmToggle.on('change', executionContextChange );
 			$web3Toggle.on('change', executionContextChange );
-			$web3endpoint.on('change', compile );
+			$web3endpoint.on('change', function(){
+				var endpoint = $('#web3Endpoint').val();
+				web3.setProvider( new web3.providers.HttpProvider( endpoint ) );
+				compile();
+			} );
 
 			function executionContextChange (ev) {
 				if (ev.target.value == 'web3' && !confirm("Are you sure you want to connect to a local ethereum node?") ) {
@@ -759,7 +763,6 @@
 					removable: false,
 					getAddress: function(){ return $('#txorigin').val(); },
 					removable_instances: true,
-					web3endpoint: $('#web3Endpoint').val(),
 					renderOutputModifier: function(contractName, $contractOutput) {
 						var contract = data.contracts[contractName];
 						return $contractOutput