Bugbyte - Issue 369

Problem

class ChatApp {
  constructor() {
    this.keywordRegex = /hello|hi|hey/g;
  }

  receiveMessage(message) {
    if (this.keywordRegex.test(message)) {
      this.sendGreeting();
    }
  }

  sendGreeting() {
    console.log("ChatApp: Hello, how can I assist you today?");
  }
}

let chatApp = new ChatApp();

chatApp.receiveMessage("hi, how are you?");
chatApp.receiveMessage("hello, can you help me?");

Solution

chatApp.receiveMessage("hi, how are you?"); // "ChatApp: Hello, how can I assist you today?"
chatApp.receiveMessage("hello, can you help me?"); // Logs nothing

In JavaScript, RegExp objects with the g (global) flag retain state between matches due to the lastIndex property, which can lead to unexpected results when reused across different inputs.

The solution is to create a fresh RegExp object for each incoming message, ensuring proper recognition and response to all greetings.

class ChatApp {
  receiveMessage(message) {
    let keywordRegex = /hello|hi|hey/g;
    if (keywordRegex.test(message)) {
      this.sendGreeting();
    }
  }

  sendGreeting() {
    console.log("ChatApp: Hello, how can I assist you today?");
  }
}

let chatApp = new ChatApp();

chatApp.receiveMessage("hi, how are you?"); // "ChatApp: Hello, how can I assist you today?"
chatApp.receiveMessage("hello, can you help me?"); // "ChatApp: Hello, how can I assist you today?"