But look at webos: it's main language is html/css/js, but extended.
{kind: "Control", layoutKind: "HFlexLayout", style: "width: 500px; height: 100px;", pack: "center", align: "start", components: [ {kind: "Button", caption: "Open", onclick: "openPopup"}, {kind: "Button", caption: "Close", onclick: "closePopup"} ] }
But you still can use Qt, C++ and so on. But if there's no js framework, no qt, then the whole platform is a shame