QML Coding Style Checker

There seems to be a new code formatter called qmlfmt.

See on github: https://github.com/jesperhh/qmlfmt

Sadly, it doesn't seem to offer a lot of options for now.

Since Qt 5.15, a new tool qmlformat is shipped which automatically formats any QML file according to the QML Coding Conventions.

Source: Qt 5.15 release notes

As far as I know QtCreator works well enough with QML. You can specify a coding style you'd like the editor to adhere to. Then use Tools > Reformat File to format the style.