@polymer/iron-selector

Demo and API docs

<iron-selector>

iron-selector is an element which can be used to manage a list of elements that can be selected. Tapping on the item will make the item selected. The selected indicates which item is being selected. The default is to use the index of the item.

Example:

  <iron-selector selected="0">
    <div>Item 1</div>
    <div>Item 2</div>
    <div>Item 3</div>
  </iron-selector>

If you want to use the attribute value of an element for selected instead of the index, set attrForSelected to the name of the attribute. For example, if you want to select item by name, set attrForSelected to name.

Example:

  <iron-selector attr-for-selected="name" selected="foo">
    <div name="foo">Foo</div>
    <div name="bar">Bar</div>
    <div name="zot">Zot</div>
  </iron-selector>

You can specify a default fallback with fallbackSelection in case the selected attribute does not match the attrForSelected attribute of any elements.

Example:

    <iron-selector attr-for-selected="name" selected="non-existing"
                   fallback-selection="default">
      <div name="foo">Foo</div>
      <div name="bar">Bar</div>
      <div name="default">Default</div>
    </iron-selector>

Note: When the selector is multi, the selection will set to fallbackSelection iff the number of matching elements is zero.

iron-selector is not styled. Use the iron-selected CSS class to style the selected element.

Example:

  <style>
    .iron-selected {
      background: #eee;
    }
  </style>

  ...

  <iron-selector selected="0">
    <div>Item 1</div>
    <div>Item 2</div>
    <div>Item 3</div>
  </iron-selector>

Notable breaking changes between 1.x and 2.x (hybrid):

IronSelectableBehavior

• IronSelectableBehavior no longer updates its list of items synchronously when it is connected to avoid triggering a situation introduced in the Custom Elements v1 spec that might cause custom element reactions to be called later than expected.

  If you are using an element with IronSelectableBehavior and ...

  1. are reading or writing properties of the element that depend on its items (items, selectedItems, etc.)
  2. are performing these accesses after the element is created or connected (attached) either synchronously or after a timeout

  ... you should wait for the element to dispatch an iron-items-changed event instead.

• Polymer.dom.flush() no longer triggers the observer used by IronSelectableBehavior to watch for changes to its items. You can call forceSynchronousItemUpdate instead or, preferably, listen for the iron-items-changed event.

IronMultiSelectableBehavior

• All breaking changes to IronSelectableBehavior listed above apply to IronMultiSelectableBehavior.
• selectedValues and selectedItems now have empty arrays as default values. This may cause bindings or observers of these properties to trigger at start up when they previously had not.