getValue() {
		if (dom.matches(this.node, 'select') || dom.matches(this.node, 'input'))
			return this.node.value;

		return null;
	}
Read the current value of the input widget.

@instance
@memberof LuCI.ui.AbstractElement
@returns {string|string[]|null}
The current value of the input element. For simple inputs like text
fields or selects, the return value type will be a - possibly empty -
string. Complex widgets such as `DynamicList` instances may result in
an array of strings or `null` for unset values.