Bug: Enter Press After ‘//’ Breaks Line and Converts Code to Comment in JavaScript

[Notdutra]

Does this issue occur when all extensions are disabled?: Yes

• VS Code Version: 1.97.2
• OS Version: macOS 15.4

Steps to Reproduce:

1. Open a new .js file in VSCode.
2. Type let string = '//this is a string'.charAt(0).
3. Place the cursor anywhere after the // in the string (e.g., between // and this, or after string before .charAt).
4. Press Enter.

Expected Behavior:

• The line should split normally, e.g.:
  let string = '//this is a string'.charAt(0)
  or:
  let string = '//this is a string' .charAt(0)

Actual Behavior:

• VS Code inserts a comment on the next line whenever Enter is pressed after //, breaking the code:
  let string = '//this // is a string'.charAt(0)
  or:
  let string = '//this is a string' // .charAt(0)

Additional Notes:
This bug occurs when you press Enter after “//” on the same line in a JavaScript file, causing the rest of the line to be treated as a comment, even with all extensions disabled and formatting settings off.

It was discovered during a real scenario with axios.get(“http://localhost/index”).then(). Pressing Enter after “//” in the URL or before “.then()” triggers the bug, which happens often when formatting HTTP request code. For example:
axios.get(“http://local
// host/index”).then()
Or
axios.get(“http://localhost/index”)
// .then()

• Strings without “//” (e.g., (‘test’), (’/test’)) split fine.

• Tested with default and minimal settings.json—issue persists even on a clean Insiders install.

• This isn’t just about obscure string splitting; it disrupts real-world coding like breaking up long URL arguments or promise chains.