Control Class

The control keeps a list of attached listeners and their handlers, making it easier to remove them when the control is disposed (see the dispose and removeEventListener methods).

Failing to remove event listeners may cause memory leaks.

The passive parameter is set to false by default, which means the event handler may call event.preventDefault(). If you are adding passive handlers to touch or wheel events, setting this parameter to true will improve application performance.

For details on passive event listeners, please see Improving scrolling performance with passive listeners.

This method should be called by constructors of templated controls. Therefore, this method is not available. It is responsible for binding the template parts to the corresponding control members.

For example, the code below applies a template to an instance of an InputNumber control. The template must contain elements with the 'wj-part' attribute set to 'input', 'btn-inc', and 'btn-dec'. The control members '_tbx', '_btnUp', and '_btnDn' will be assigned references to these elements.

this.applyTemplate('wj-control wj-inputnumber', templateString, {
  _tbx: 'input',
  _btnUp: 'btn-inc',
  _btnDn: 'btn-dec'
}, 'input');

@param classNames Names of classes to add to the control's host element. @param template An HTML string that defines the control template. @param parts A dictionary of part variables and their names. @param namePart Name of the part to be named after the host element. This determines how the control submits data when used in forms.

The control will not be updated until the function has been executed. This method ensures endUpdate is called even if the function throws an exception.

The dispose method automatically removes any event listeners added with the addEventListener method.

Calling the dispose method is important in applications that create and remove controls dynamically. Failing to dispose of the controls may cause memory leaks.

This method traverses up the class hierarchy to find the nearest ancestor that specifies a control template. For example, if you specify a prototype for the ComboBox control, which does not specify a template, it will override the template defined by the DropDown base class (the nearest ancestor that does specify a template).

This method allows you to initialize controls using plain data objects instead of setting the value of each property in code.

For example:

grid.initialize({
  itemsSource: myList,
  autoGenerateColumns: false,
  columns: [
    { binding: 'id', header: 'Code', width: 130 },
    { binding: 'name', header: 'Name', width: 60 }
  ]
});

// is equivalent to
grid.itemsSource = myList;
grid.autoGenerateColumns = false;
// etc.

The initialization data is type-checked as it is applied. If the initialization object contains unknown property names or invalid data types, this method will throw.

If the event handler cancels the event, the control will keep the invalid input and the focus.