Need to add try catch block - node.js

Question

I am new to nodejs so below is my code, I need to add try-catch blocks for my below code need some help to do this because new to this things, below is my websocket code newly created I need to add try-catch blocks for this , please help me out anyone
var WebSocket = require('ws');
//var Stomp = require('stompjs');
function CustomWebSocketListener(config) {
RED.nodes.createNode(this,config);
var node = this;
node.on('input', function(msg) {
let temp =msg.payload;
let urllist = temp.url;
let urls=[]
if(global.websocket!=null || global.websocket!=undefined){
let connections=global.websocket;
console.log("global")
if(global.isAccessTokenExpired){
for(let k in connections) {
connections[k].close();
connections[k].reconnect=false
console.log('connection closed:::');
}
urls=urllist;
}
else{
for(let i=0;i<urllist.length;i++){
let group=urllist[i].split("/")[7].split("?");
if(!connections[group[0]]){
urls.push(urllist[i])
}
}
}
}
else{
urls=urllist;
}
console.log("urls.length::::"+urls.length)
if(urls.length > 0){
for(let i=0;i<urls.length;i++){
console.log(':::::::for loop:::::::')
console.log('url----'+urls[i])
function connect(urlIndex) {
let ws;
if(urlIndex!=undefined||urlIndex!=null){
ws = new WebSocket(urls[urlIndex]);
}
else{
ws = new WebSocket(urls[i]);
}
ws.index=i;
ws.reconnect=true;
ws.onopen = function() {
};
ws.onmessage = function(e) {
console.log('Message:', e.data);
console.log('Socket is closed. Reconnect will be attempted in 30 second.', e.reason);
setTimeout(function() {
console.log("onclose ----ws reconnect"+ws.reconnect)
if(ws.reconnect){
console.log("inside if reconnect")
connect(ws.index);
}
}, 30000);
};
ws.onerror = function(err) {
console.error('Socket encountered error: ', err.message, 'Closing socket');
ws.close();
};
if(global.websocket==null || global.websocket==undefined){
global.websocket={};
console.log(global.websocket)
global.websocket[urls[i]]=ws;
}
else{
global.websocket[urls[i]]=ws;
}
}
connect();
}
}
});
}
RED.nodes.registerType("custom-websocketlistener",CustomWebSocketListener);
}
Thanks for anyone who would help me out with this

Answer 1

you can directly use where you want like this...
try{
//whatever you want
}
catch(e){
//whatever you want
}
In your code you can use like this
try {
RED.nodes.createNode(this, config)
var node = this
node.on('input', function(msg) {
let temp = msg.payload
let urllist = temp.url
let urls = []
if (global.websocket != null || global.websocket != undefined) {
let connections = global.websocket
console.log('global')
if (global.isAccessTokenExpired) {
for (let k in connections) {
connections[k].close()
connections[k].reconnect = false
console.log('connection closed:::')
}
urls = urllist
} else {
for (let i = 0; i < urllist.length; i++) {
let group = urllist[i].split('/')[7].split('?')
if (!connections[group[0]]) {
urls.push(urllist[i])
}
}
}
} else {
urls = urllist
}
console.log('urls.length::::' + urls.length)
if (urls.length > 0) {
for (let i = 0; i < urls.length; i++) {
console.log(':::::::for loop:::::::')
console.log('url----' + urls[i])
function connect(urlIndex) {
let ws
if (urlIndex != undefined || urlIndex != null) {
ws = new WebSocket(urls[urlIndex])
} else {
ws = new WebSocket(urls[i])
}
ws.index = i
ws.reconnect = true
ws.onopen = function() {}
ws.onmessage = function(e) {
console.log('Message:', e.data)
console.log('Socket is closed. Reconnect will be attempted in 30 second.', e.reason)
setTimeout(function() {
console.log('onclose ----ws reconnect' + ws.reconnect)
if (ws.reconnect) {
console.log('inside if reconnect')
connect(ws.index)
}
}, 30000)
}
ws.onerror = function(err) {
console.error('Socket encountered error: ', err.message, 'Closing socket')
ws.close()
}
if (global.websocket == null || global.websocket == undefined) {
global.websocket = {}
console.log(global.websocket)
global.websocket[urls[i]] = ws
} else {
global.websocket[urls[i]] = ws
}
}
connect()
}
}
})
} catch (e) {
console.log(e)
}
}