Скачать или смотреть How to Fix the Invalid or Unexpected Token Error When Invoking a Private Method in JavaScript

Learn how to resolve the "Invalid or unexpected token" error that occurs when invoking a private method in JavaScript. Enhance your understanding of private methods in JavaScript classes to write better, error-free code.
---
How to Fix the Invalid or Unexpected Token Error When Invoking a Private Method in JavaScript

JavaScript has come a long way in implementing object-oriented programming features. One of the modern additions to its syntax is the ability to declare private methods within classes. However, improper use of these features can sometimes lead to frustrating errors such as the "Invalid or unexpected token" error. Let's dive into how you can fix this error when it arises due to invoking a private method incorrectly.

Understanding Private Methods

In JavaScript, a private method is a function defined within a class using the `` symbol as a prefix. This indicates that the method is only accessible from within the class itself and not from outside or even derived classes. Here's a simple example of a class with a private method:

[[See Video to Reveal this Text or Code Snippet]]

Common Errors and Fixes

Syntax Error When Invoking Private Methods Directly

One of the most common causes of the "Invalid or unexpected token" error is trying to directly invoke a private method from outside the class. For example:

[[See Video to Reveal this Text or Code Snippet]]

Attempting to run this line will result in an error because privateMethod is not accessible outside the MyClass definition. The fix here is straightforward: ensure that any calls to private methods are made within the class context, as shown earlier.

Typos and Misnaming

Another reason you could encounter this error is due to typos or incorrect method names. Ensure your method names match exactly, including the `` symbol. The following would be incorrect and cause errors:

[[See Video to Reveal this Text or Code Snippet]]

Correcting the method name ensures that JavaScript can find and invoke the method properly.

Incorrect Use of the Symbol

Ensure you're using the `` symbol correctly. This symbol is required both when defining the method and when invoking it within the class. Omitting it in either place results in errors:

[[See Video to Reveal this Text or Code Snippet]]

Adding the `` symbol to this.privateMethod() resolves the error.

Conclusion

Fixing the "Invalid or unexpected token" error when invoking private methods in JavaScript involves ensuring correct usage of the `` symbol and avoiding direct calls to private methods from outside their class. By adhering to these guidelines, you can write more robust and error-free JavaScript code utilizing the capabilities of object-oriented programming.