Allow to specify file format

[Akiyamka]

Currently, Biome attempts to determine the file format based on the file extension. This covers most cases but not all - extensions can be non-standard or may be completely absent. For example, when using the override function in Chrome and Firefox, the browser creates a file with a name that SHOULD correspond to the path from which this file was obtained

For instance, ./header.js?adTagId=8.

Although I can manually specify for the editor that this is a JavaScript file by selecting the format, Biome in this case cannot format it. The error message contains the following:

⚠ Biome could not determine the language for the file extension js?adTagId=8

Steps and logs

The simplest way to reproduce the issue is to try to format such a file via the command line:

$ npx @biomejs/biome format --write "./header.js?adTagId=8" --verbose --javascript-formatter-enabled=true --files-ignore-unknown=false


  ⚠ Biome could not determine the language for the file extension js?adTagId=8

  Verbose advice

    ℹ If you want to turn off this diagnostic, consider using --files-ignore-unknown from the CLI, or files.ignoreUnknown from the configuration file.


Formatted 0 files in 94µs. No fixes applied.
Found 1 warning.
 VERBOSE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ Files processed:

  ⚠ The list is empty.


 VERBOSE  ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ℹ Files fixed:

  ⚠ The list is empty.


internalError/io ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  ✖ No files were processed in the specified paths.

Possible solution:

Add a parameter to manually specify the file format by indicating the associated extension, for example:

$ npx @biomejs/biome format --write "./header.js?adTagId=8" --lang=js

[ematipico]

You can achieve that via standard input: cat 'header.js?adTagId=8' | biome format --write --stdin-file-path=file.js