QmlWeb already has built-in components:
Component: QMLComponent,
QMLDocument: QMLComponent,
MouseArea: QMLMouseArea,
Image: QMLImage,
AnimatedImage: QMLAnimatedImage,
BorderImage: QMLBorderImage,
Item: QMLItem,
Column: QMLColumn,
Row: QMLRow,
Grid: QMLGrid,
Flow: QMLFlow,
Rotation: QMLRotation,
Scale: QMLScale,
Translate: QMLTranslate,
FontLoader: QMLFontLoader,
Text: QMLText,
Rectangle: QMLRectangle,
Repeater: QMLRepeater,
ListModel: QMLListModel,
ListElement: QMLListElement,
State: QMLState,
PropertyChanges: QMLPropertyChanges,
Transition: QMLTransition,
Timer: QMLTimer,
SequentialAnimation: QMLSequentialAnimation,
ParallelAnimation: QMLParallelAnimation,
NumberAnimation: QMLNumberAnimation,
Behavior: QMLBehavior,
TextInput: QMLTextInput,
Button: QMLButton,
TextArea: QMLTextEdit, // non-standard, to be removed!
TextEdit: QMLTextEdit,
CheckBox: QMLCheckbox