Fix JavaScript SyntaxError: Invalid or unexpected token - 2025 Guide

Posted on: April 3, 2025

Encountered a "SyntaxError: Invalid or unexpected token" in JavaScript? This error can stop your code dead in its tracks. Let’s explore why it happens and how to fix it fast in this 2025 guide!

What Causes "SyntaxError: Invalid or unexpected token"?

This error occurs when JavaScript encounters a character or sequence it can’t parse. Common culprits include:

• Mismatched Symbols: Unclosed brackets, parentheses, or quotes.
• Illegal Characters: Copy-pasted code with hidden special characters (e.g., zero-width spaces).
• Incorrect Syntax: Using reserved keywords or invalid operators.

Check this demo (open console with F12):

Here, an unclosed bracket or invalid character triggers the error.

How to Fix It: 3 Solutions

Here’s how to resolve this error step-by-step:

(Diagram: Developer writes code, gets error, fixes syntax, runs successfully.)

Solution 1: Check for Mismatched Symbols

Ensure all brackets, quotes, and parentheses are properly closed:

// Wrong
let data = { name: "John" ; // Missing closing brace
console.log(data);

// Fixed
let data = { name: "John" };
console.log(data); // { name: "John" }

Use an editor with bracket matching to spot these errors quickly.

Solution 2: Remove Illegal Characters

Watch out for hidden characters from copy-pasting:

// Wrong (contains invisible zero-width space)
let text = "HelloWorld"; // SyntaxError due to hidden character
console.log(text);

// Fixed
let text = "HelloWorld";
console.log(text); // "HelloWorld"

Tip: Retype the line manually or use a linter to spot these issues.

Solution 3: Correct Syntax Mistakes

Avoid using reserved keywords or invalid syntax:

// Wrong
let class = "error"; // 'class' is a reserved keyword
console.log(class);

// Fixed
let className = "error";
console.log(className); // "error"

Check JavaScript reserved words to avoid conflicts.

Quick Checklist

• Unclosed symbols? (Check brackets and quotes)
• Hidden characters? (Retype or use a linter)
• Syntax errors? (Avoid reserved words)

Conclusion

The "SyntaxError: Invalid or unexpected token" is a common JavaScript hiccup, but with these 2025 solutions, you’ll debug it easily. Use these tips to keep your code running smoothly. Got another error? Let us know in the comments!