How to use clearInterval? - node.js

Question

I am new to nodejs and try to send message to the server.
When I input 1, it will set message to the server every 3 second. When I input 2, it will stop sending the message.
However, it keeps sending message to the server when I input 2. How should I use clearInterval
this is the script.
var WebSocket = require('ws');
var ws = new WebSocket("ws://localhost:8075");
ws.onopen = ('connect', function(connect) {
let obj={};
obj.body='connect';
ws.send(JSON.stringify(obj));
});
process.stdin.resume();
process.stdin.setEncoding('utf8');
process.stdin.on('data', function (message) {
if (message.trim() == '1') {
var setintv = setInterval(function () {
let obj2 = {};
obj2.name = 'data'
message = '123';
obj2.body = message;
ws.send(JSON.stringify(obj2), console.log.bind(null, 'Sent : ', message));
}, 3000);
}else if(message.trim() == '2') {
clearInterval(setintv);
}
else {
let obj = {};
obj.name = 'data'
message = message.trim();
obj.body = message;
ws.send(JSON.stringify(obj), console.log.bind(null, 'Sent : ', message));
}
});

Answer 1

The variable setintv will not be available in the block where you call clearInterval. If you however declare it as a global it will be, for example:
var WebSocket = require('ws');
var ws = new WebSocket("ws://localhost:8075");
ws.onopen = ('connect', function(connect) {
let obj={};
obj.body='connect';
ws.send(JSON.stringify(obj));
});
var setintv = null;
process.stdin.resume();
process.stdin.setEncoding('utf8');
process.stdin.on('data', function (message) {
if (message.trim() == '1') {
// Save for later use.
setintv = setInterval(function () {
let obj2 = {};
obj2.name = 'data'
message = '123';
obj2.body = message;
ws.send(JSON.stringify(obj2), console.log.bind(null, 'Sent : ', message));
}, 3000);
}else if(message.trim() == '2') {
if (setintv !== null) {
clearInterval(setintv);
setintv = null; // We're done with this now.
}
}
else {
let obj = {};
obj.name = 'data'
message = message.trim();
obj.body = message;
ws.send(JSON.stringify(obj), console.log.bind(null, 'Sent : ', message));
}
});