How to send data to whoever it came from Socket.io?

Question

JavaScript

I found in the documentation that if you write not io, but socket on the server side, it will work, but no, or I'm dumb, I'm doing calculations on the server side, so the script below calculates the player's xp, but it distributes it to everyone, but I need to have Each player had their own HP.
I thought to do it through socket.id, but unfortunately it did not work. Help

//Хп игрока   	
   	socket.on('user fight', function(data) {
   		user_hp = data;
   		if(user_hp<=0) {
   			user_hp = max_user_hp;
   			socket.emit('lose');
   		}
        x2 = user_hp/max_user_hp*100;
        socket.emit('user hp', user_hp);
        if(user_hp>0) socket.emit('user hp line width', x2);
   		if(user_hp<=0) socket.emit('user hp line width', 0);
   		if(hp+user_hp <= 0) {
   			socket.emit('draw');
   		}
   	});
   	
   	//io.sockets.connected[socket.id].emit('class', 'alert');
   	
   	socket.on('hp line for all', function(data) {
        x2 = user_hp/max_user_hp*100;
   		socket.emit('user hp line width', x2);
   		if(user_hp<=0) {
   			socket.emit('user hp line width', 0);
   			socket.emit('lose');
   		}
   		if(hp+user_hp <= 0) {
   			socket.emit('draw');
   		}
   	});
   		
   	//end

Answer 1

With socket.emit, as you are doing.

io.on('connect', function(socket) {
  socket.emit('name', ...); // socket = переменная с текущим коннектом отдающаяся в каллбеке события connect.
})

Perhaps you are catching events incorrectly on the client side.