Allow to unsubscribe from ws topic

doc/websocket-client.md

@@ -37,6 +37,10 @@ to the server once connection has been lost.
 - `topics` {String|Array} Single topic as string or multiple topics as array of strings.
 Subscribe to one or multiple topics. See [available topics](#available-topics)
 
+### ws.unsubscribe(topics)
+
+- `topics` {String|Array} Single topic as string or multiple topics as array of strings.
+Unsubscribe from one or multiple topics.
 
 ### ws.close()
 

lib/websocket-client.js

@@ -50,6 +50,17 @@ module.exports = class WebsocketClient extends EventEmitter {
     this.ws.send(msgStr);
   }
 
+  unsubscribe(topics) {
+    if(!Array.isArray(topics)) topics = [topics];
+
+    const msgStr = JSON.stringify({
+      op: 'unsubscribe',
+      'args': topics
+    });
+
+    this.ws.send(msgStr);
+  }
+
   close() {
     this.logger.info('Closing connection', {category: 'bybit-ws'});
     this.readyState = READY_STATE_CLOSING;