Resolving “SyntaxError: Invalid or unexpected token” in JavaScript

Introduction

The SyntaxError: Invalid or unexpected token error is a common error encountered in JavaScript programming. This error commonly occurs when the JavaScript engine encounters tokens or pieces of the codes that it does not expect, resulting in the interrupting of the execution of the code.

Casing Scenarios

Let’s have a look at some common scenarios where this error can occur:

1. Unexpected Identifier

This occurs when there is an unexpected naming of a function or variable, or when it’s followed by a non-valid character.

function

In the above example, our function has no name which is unexpected, leading to a SyntaxError.

2. Inappropriate Use of Special Characters

Special characters must be handled appropriately in JavaScript. In the string below, we have failed to escape the quotation marks around the word “hello.”

var greeting = "Say "hello" to him";

3. Unmatched parentheses, brackets, or braces

Always ensure all opening brackets have a closing pair. Leaving them unmatched results in a SyntaxError.

if (response.data.status = 'success' {
   console.log('Success!');
}

Solving The Error

Most of these errors can be solved by keeping track of identifiers in your code and making sure they are named correctly and used correctly according to JavaScript rules. Also, it’s important to pay attention to the use of special characters and ensure they are being escaped correctly when inside strings.

The unmatched parentheses, brackets, or braces can be addressed by ensuring a closing pair for every opening pair. Editors with bracket matching features can be helpful in mitigating such errors.

Conclusion

In conclusion, always ensure correct syntax to avoid errors. Use of syntax highlighting editors, linters, or other code quality tools can help point out these areas before running your code. If you’re still stuck, don’t hesitate to reach out to the relevant coding communities for help, they are always ready to assist.