JavaScript Formatter accepts clearly invalid syntax without an error

[baixiangcpp]

Summary

JavaScript Formatter accepts clearly invalid JavaScript and presents it as output instead of showing a syntax error. The page's own guidance says syntax errors should prevent formatting.

Affected route: https://byteflow.tools/en/javascript-formatter

Reproduction

1. Enter this input:

   const = ;
   

2. Click Format.

Expected:

• show a syntax/parse error;
• clear or invalidate the output;
• do not enable Copy/Download for invalid formatted code.

Actual:

• no error is shown;
• the output is the same invalid text: const = ;;
• Copy Output remains enabled.

A second malformed sample, function (, was also accepted and returned as function( without an error.

Control case

A valid input such as function add(a,b){return a+b;}const value=add(1,2); formatted correctly and copied correctly. The issue is the missing rejection/error path for malformed syntax.

Environment

• Browser: Chrome via cloud browser
• Tested: 2026-08-18