Ubuntu – How to check if a property is undefined in qml

toolbaritems has been deprecated in Ubuntu.Components 1.1, so its use is strongly discouraged. It is maintained for backward compatibility, but the right way to add items to the header toolbar is now using head.actions.

The main difference between head.actions and toolbaritems is that you don't need anymore to add ToolbarButton items and then set their action property. All you need with head.actions is to specify a list of actions and then they will be automatically shown according to Ubuntu Touch patterns.

An example that shows how to use head property is the following (from official documentation):

import QtQuick 2.0
import Ubuntu.Components 1.1

MainView {
     width: units.gu(48)
     height: units.gu(60)
     Page {
         title: i18n.tr("Example page")
         Label {
             anchors.centerIn: parent
             text: i18n.tr("Hello world!")
        }
        head.actions: [
             Action {
                 iconName: "search"
                 text: i18n.tr("Search")
             },
             Action {
                 iconName: "contacts"
                 text: i18n.tr("Contacts")
             }
        ]
    }
}

There are some other useful settings for PageHead (e.g. custom Item to show instead of the title), so I'd suggest you to take a look at this page.

If you are running Ubuntu 14.04 LTS, these new APIs are not available, due to their dependence on Qt 5.3. You can solve this issue following this link .

You can use almost all the javascript syntax in QML (See http://qt-project.org/doc/qt-5/ecmascript.html).

The fastest method is Math.round(<NUM> * 100) / 100

But (<NUM>).toFixed(2) works (but is too slow according to this question on SO)

The following snippet of code presents both implementations:

import QtQuick 2.0
import Ubuntu.Components 0.1

MainView {
    id: root
    width: units.gu(50)
    height: units.gu(80)

    property var my_number: Math.round(33.088117576394794 * 100) / 100;
    property var my_number2: (33.088117576394794).toFixed(2);

    Component.onCompleted: {
        console.log(my_number)
        console.log(my_number2)
    }
}