检查键是否存在于数组中并替换其值

Question

CLIENT CODE

I am sending an id of a client from the client side using

var socket = io.connect('http://localhost:8080?token='+userID);

and getting it on the server in my io.on('connection') function using

SERVER CODE

let token = socket.handshake.query.token;

so now I have the userID stored in the variable token .

Also I am getting the connected socket id and storing it like

var id = socket.id;

Then I am storing the userID and the socketID in an array as key value pair.

var item = {};
item[token] = id;

This is an array I am pushing it into(the array is declared outside the on connection function)

keyPairArray.push(item);

So I am getting an array like this when two people are connected.

[ { '10': 'HvlunYNFCcF5vK0-AAAA' },
  { '1456': '17XF7mbh4vYr2WUSAAAB' } ]

But when any user reloads the page the array gets like

[ { '10': 'HvlunYNFCcF5vK0-AAAA' },
  { '1456': '17XF7mbh4vYr2WUSAAAB' },
  { '1456': 'tIhvkxFbSSAQEckWAAAC' } ]

Same user Id but different socket id's .

The socket id changes every time the user reloads the page or opens the page in another tab and the same UserID is appended into the array with a different socket id .

I don't want to insert the same user again. If the user reloads the page, I want it to check the userId which is the key in the array and replace the old socket id with the newly generated one.

This is the code that I tried with no luck

var checkKeyPair = keyPairArray.some(function(item){
    return item[token] === id;
});

if(checkKeyPair){
    console.log("Hello");
}else{
    keyPairArray.push(item);
    console.log(keyPairArray);
}

Answer 1

Try this (if ES6 is not a problem):

let token = socket.handshake.query.token;
var id = socket.id;
var item = { [token]: id };
var index = keyPairArray.findIndex(it => Object.keys(it)[0] === token);
if (index === -1) {
    keyPairArray.push(item);
} else {
    keyPairArray[index] = item;
}

Answer 2

You can combine Array#some with Object.keys to check if there is an user with given userId, something like that:

 const users = [{ '10': 'HvlunYNFCcF5vK0-AAAA' }, { '1456': '17XF7mbh4vYr2WUSAAAB' } ]; function checkIfUserExists(userId) { return users.some((user) => Object.keys(user).indexOf(userId) > -1) } console.log(checkIfUserExists('10')); console.log(checkIfUserExists('11')); 

Answer 3

 var users = [{ '10': 'HvlunYNFCcF5vK0-AAAA' }, { '1456': '17XF7mbh4vYr2WUSAAAB' } ]; function saveUser(newUserId) { users.forEach(function(key) { if (Object.keys(key)[0] == newUserId) console.log('user exists'); else { var item = {}; item[newUserId] = 'fsdfsdgdfsgdfhgf55665hftgh56'; users.push(item); } }); } saveUser('1456');