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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 ...
- are reading or writing properties of the element that depend on its
items (
items
, selectedItems
, etc.) - 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.