Dropdown

Dropdown also known as Select, is used to choose an item from a collection of options.

Import #


import { DropdownModule } from 'primeng/dropdown';

Basic #

Dropdown is used as a controlled component with ngModel property along with an options collection. Label and value of an option are defined with the optionLabel and optionValue properties respectively. Note that, when options are simple primitive values such as a string array, no optionLabel and optionValue would be necessary.


<p-dropdown [options]="cities" [(ngModel)]="selectedCity" optionLabel="name" [showClear]="true" placeholder="Select a City"></p-dropdown>

Reactive Forms #

Dropdown can also be used with reactive forms. In this case, the formControlName property is used to bind the component to a form control.


<form [formGroup]="formGroup">
    <p-dropdown formControlName="selectedCity" [options]="cities" optionLabel="name" placeholder="Select a City"></p-dropdown>
</form>

Editable #

When editable is present, the input can also be entered with typing.


<p-dropdown [options]="cities" [(ngModel)]="selectedCity" placeholder="Select a City" [editable]="true" optionLabel="name"></p-dropdown>

Group #

Options can be grouped when a nested data structures is provided.


<p-dropdown [options]="groupedCities" [(ngModel)]="selectedCity" placeholder="Select a City" [group]="true">
    <ng-template let-group pTemplate="group">
        <div class="flex align-items-center">
            <img src="https://primefaces.org/cdn/primeng/images/demo/flag/flag_placeholder.png" [class]="'mr-2 flag flag-' + group.value" style="width: 20px" />
            <span>{{ group.label }}</span>
        </div>
    </ng-template>
</p-dropdown>

Template #

Both the selected option and the options list can be templated to provide customizated representation. Use selectedItem template to customize the selected label display and the item template to change the content of the options in the dropdown panel. In addition when grouping is enabled, group template is available to customize the option groups. All templates get the option instance as the default local template variable.


<p-dropdown [options]="countries" [(ngModel)]="selectedCountry" optionLabel="name" [showClear]="true" placeholder="Select a Country">
    <ng-template pTemplate="selectedItem">
        <div class="flex align-items-center gap-2" *ngIf="selectedCountry">
            <img src="https://primefaces.org/cdn/primeng/images/demo/flag/flag_placeholder.png" [class]="'flag flag-' + selectedCountry.code.toLowerCase()" style="width: 18px"/>
            <div>{{ selectedCountry.name }}</div>
        </div>
    </ng-template>
    <ng-template let-country pTemplate="item">
        <div class="flex align-items-center gap-2">
            <img src="https://primefaces.org/cdn/primeng/images/demo/flag/flag_placeholder.png" [class]="'flag flag-' + country.code.toLowerCase()" style="width: 18px"/>
            <div>{{ country.name }}</div>
        </div>
    </ng-template>
</p-dropdown>

Filter #

Dropdown provides built-in filtering that is enabled by adding the filter property.


<p-dropdown [options]="countries" [(ngModel)]="selectedCountry" optionLabel="name" [filter]="true" filterBy="name" [showClear]="true" placeholder="Select a Country">
    <ng-template pTemplate="selectedItem">
        <div class="flex align-items-center gap-2" *ngIf="selectedCountry">
            <img src="https://primefaces.org/cdn/primeng/images/demo/flag/flag_placeholder.png" [class]="'flag flag-' + selectedCountry.code.toLowerCase()" style="width: 18px"/>
            <div>{{ selectedCountry.name }}</div>
        </div>
    </ng-template>
    <ng-template let-country pTemplate="item">
        <div class="flex align-items-center gap-2">
            <img src="https://primefaces.org/cdn/primeng/images/demo/flag/flag_placeholder.png" [class]="'flag flag-' + country.code.toLowerCase()" style="width: 18px"/>
            <div>{{ country.name }}</div>
        </div>
    </ng-template>
</p-dropdown>

Virtual Scroll #

VirtualScrolling is an efficient way of rendering the options by displaying a small subset of data in the viewport at any time. When dealing with huge number of options, it is suggested to enable VirtualScrolling to avoid performance issues. Usage is simple as setting virtualScroll property to true and defining virtualScrollItemSize to specify the height of an item.


<p-dropdown [options]="items" [(ngModel)]="selectedItem" placeholder="Select Item" 
    [virtualScroll]="true" [virtualScrollItemSize]="38"></p-dropdown>

Disabled #

When disabled is present, the element cannot be edited and focused.


<p-dropdown [options]="cities" [(ngModel)]="selectedCity" placeholder="Select a City" optionLabel="name" [disabled]="true"></p-dropdown>

Float Label #

A floating label appears on top of the input field when focused.

Select a City


<span class="p-float-label">
    <p-dropdown [options]="cities" [(ngModel)]="selectedCity" placeholder="Select a City" optionLabel="name" inputId="float-label"></p-dropdown>
    <label for="float-label">Select a City</label>
</span>

Style #

Following is the list of structural style classes, for theming classes visit theming page.

Name	Element
p-dropdown	Container element.
p-dropdown-clearable	Container element when showClear is on.
p-dropdown-label	Element to display label of selected option.
p-dropdown-trigger	Icon element.
p-dropdown-panel	Icon element.
p-dropdown-items-wrapper	Wrapper element of items list.
p-dropdown-items	List element of items.
p-dropdown-item	An item in the list.
p-dropdown-filter-container	Container of filter input.
p-dropdown-filter	Filter element.
p-dropdown-open	Container element when overlay is visible.

Accessibility #

Screen Reader

Value to describe the component can either be provided with ariaLabelledBy or ariaLabel props. The dropdown element has a combobox role in addition to aria-haspopup and aria-expanded attributes. If the editable option is enabled aria-autocomplete is also added. The relation between the combobox and the popup is created with aria-controls and aria-activedescendant attribute is used to instruct screen reader which option to read during keyboard navigation within the popup list.

The popup list has an id that refers to the aria-controls attribute of the combobox element and uses listbox as the role. Each list item has an option role, an id to match the aria-activedescendant of the input element along with aria-label, aria-selected and aria-disabled attributes.

If filtering is enabled, filterInputProps can be defined to give aria-* props to the filter input element.


<span id="dd1">Options</span>
<p-dropdown ariaLabelledBy="dd1"></p-dropdown>

<p-dropdown ariaLabel="Options"></p-dropdown>

Closed State Keyboard Support

Key	Function
tab	Moves focus to the dropdown element.
space	Opens the popup and moves visual focus to the selected option, if there is none then first option receives the focus.
down arrow	Opens the popup and moves visual focus to the selected option, if there is none then first option receives the focus.
up arrow	Opens the popup and moves visual focus to the selected option, if there is none then last option receives the focus.

Popup Keyboard Support

Key	Function
tab	Moves focus to the next focusable element in the popup, if there is none then first focusable element receives the focus.
shift + tab	Moves focus to the previous focusable element in the popup, if there is none then last focusable element receives the focus.
enter	Selects the focused option and closes the popup.
space	Selects the focused option and closes the popup.
escape	Closes the popup, moves focus to the dropdown element.
down arrow	Moves focus to the next option, if there is none then visual focus does not change.
up arrow	Moves focus to the previous option, if there is none then visual focus does not change.
right arrow	If the dropdown is editable, removes the visual focus from the current option and moves input cursor to one character left.
left arrow	If the dropdown is editable, removes the visual focus from the current option and moves input cursor to one character right.
home	If the dropdown is editable, moves input cursor at the end, if not then moves focus to the first option.
end	If the dropdown is editable, moves input cursor at the beginning, if not then moves focus to the last option.
any printable character	Moves focus to the option whose label starts with the characters being typed if dropdown is not editable.

Filter Input Keyboard Support

Key	Function
enter	Closes the popup and moves focus to the dropdown element.
escape	Closes the popup and moves focus to the dropdown element.

Dropdown API

API defines helper props, events and others for the PrimeNG Dropdown module.

Dropdown #

Dropdown also known as Select, is used to choose an item from a collection of options.

Properties #

Defines the input properties of the component.

name	type	default	description
id	string	null	Unique identifier of the component
scrollHeight	string	200px	Height of the viewport in pixels, a scrollbar is defined if height of list exceeds this value.
filter	boolean	false	When specified, displays an input field to filter the items on keyup.
name	string	null	Name of the input element.
style	Object	null	Inline style of the element.
panelStyle	Object	null	Inline style of the overlay panel element.
styleClass	string	null	Style class of the element.
panelStyleClass	string	null	Style class of the overlay panel element.
readonly	boolean	false	When present, it specifies that the component cannot be edited.
required	boolean	false	When present, it specifies that an input field must be filled out before submitting the form.
editable	boolean	false	When present, custom value instead of predefined options can be entered using the editable input field.
appendTo	any	null	Target element to attach the overlay, valid values are "body" or a local ng-template variable of another element (note: use binding with brackets for template variables, e.g. [appendTo]="mydiv" for a div element having #mydiv as variable name).
tabindex	number	0	Index of the element in tabbing order.
placeholder	string	null	Default text to display when no option is selected.
filterPlaceholder	string	null	Placeholder text to show when filter input is empty.
filterLocale	string	null	Locale to use in filtering. The default locale is the host environment's current locale.
inputId	string	null	Identifier of the accessible input element.
dataKey	string	null	A property to uniquely identify a value in options.
filterBy	string	null	When filtering is enabled, filterBy decides which field or fields (comma separated) to search against.
filterFields	any[]	null	Fields used when filtering the options, defaults to optionLabel.
autofocus	boolean	false	When present, it specifies that the component should automatically get focus on load.
resetFilterOnHide	boolean	false	Clears the filter value when hiding the dropdown.
dropdownIcon	string	null	Icon class of the dropdown icon.
optionLabel	string	null	Name of the label field of an option.
optionValue	string	null	Name of the value field of an option.
optionDisabled	string	null	Name of the disabled field of an option.
optionGroupLabel	string	label	Name of the label field of an option group.
optionGroupChildren	string	items	Name of the options field of an option group.
autoDisplayFirst	boolean	true	Whether to display the first item as the label if no placeholder is defined and value is null.
group	boolean	false	Whether to display options as grouped when nested options are provided.
showClear	boolean	false	When enabled, a clear icon is displayed to clear the value.
emptyFilterMessage	string	null	Text to display when filtering does not return any results. Defaults to global value in i18n translation configuration.
emptyMessage	string	null	Text to display when there is no data. Defaults to global value in i18n translation configuration.
lazy	boolean	false	Defines if data is loaded and interacted with in lazy manner.
virtualScroll	boolean	false	Whether the data should be loaded on demand during scroll.
virtualScrollItemSize	number	null	Height of an item in the list for VirtualScrolling.
virtualScrollOptions	ScrollerOptions	null	Whether to use the scroller feature. The properties of scroller component can be used like an object in it.
overlayOptions	OverlayOptions	null	Whether to use overlay API feature. The properties of overlay API can be used like an object in it.
ariaFilterLabel	string	null	Defines a string that labels the filter input.
ariaLabel	string	null	Used to define a aria label attribute the current element.
ariaLabelledBy	string	null	Establishes relationships between the component and label(s) where its value should be one or more element IDs.
filterMatchMode	"endsWith" \| "startsWith" \| "contains" \| "equals" \| "notEquals" \| "in" \| "lt" \| "lte" \| "gt" \| "gte"	contains	Defines how the items are filtered.
maxlength	number	null	Maximum number of character allows in the editable input field.
tooltip	string	null	Advisory information to display in a tooltip on hover.
tooltipPosition	"left" \| "top" \| "bottom" \| "right"	right	Position of the tooltip.
tooltipPositionStyle	string	absolute	Type of CSS position.
tooltipStyleClass	string	null	Style class of the tooltip.
focusOnHover	boolean	false	Fields used when filtering the options, defaults to optionLabel.
selectOnFocus	boolean	false	Determines if the option will be selected on focus.
autoOptionFocus	boolean	true	Whether to focus on the first visible or selected element when the overlay panel is shown.
autofocusFilter	boolean	true	Applies focus to the filter element when the overlay is shown.
disabled	boolean	null	When present, it specifies that the component should be disabled.
itemSize	number	null	Item size of item to be virtual scrolled.
autoZIndex	boolean	null	Whether to automatically manage layering.
baseZIndex	number	null	Base zIndex value to use in layering.
showTransitionOptions	string	null	Transition options of the show animation.
hideTransitionOptions	string	null	Transition options of the hide animation.
filterValue	string	null	When specified, filter displays with this value.
options	any[]	null	An array of objects to display as the available options.

Emitters #

Defines emit that determine the behavior of the component based on a given condition or report the actions that the component takes.

name	parameters	description
onChange	event : DropdownChangeEvent	Callback to invoke when value of dropdown changes.
onFilter	event : DropdownFilterEvent	Callback to invoke when data is filtered.
onFocus	event : Event	Callback to invoke when dropdown gets focus.
onBlur	event : Event	Callback to invoke when dropdown loses focus.
onClick	event : MouseEvent	Callback to invoke when component is clicked.
onShow	event : AnimationEvent_2	Callback to invoke when dropdown overlay gets visible.
onHide	event : AnimationEvent_2	Callback to invoke when dropdown overlay gets hidden.
onClear	event : Event	Callback to invoke when dropdown clears the value.
onLazyLoad	event : DropdownLazyLoadEvent	Callback to invoke in lazy mode to load new data.

Methods #

Defines methods that can be accessed by the component's reference.

name	parameters	description
resetFilter	null	Callback to invoke on filter reset.
show	isFocus : any	Displays the panel.
hide	isFocus : any	Hides the panel.
focus	null	Applies focus.

Templates #

Defines the templates used by the component.

name	parameters	description
item	context : { $implicit: any, // Data of the option. }	Custom header template.
selectedItem	context : { $implicit: any, // Selected option value. }	Custom selected item template.
header	null	Custom header template.
filter	context : { options: DropdownFilterOptions, // Filter options. }	Custom filter template.
footer	null	Custom footer template.
emptyfilter	null	Custom empty filter template.
empty	null	Custom empty template.
group	context : { $implicit: any, // Group option. }	Custom group template.
loader	context : { options: ScrollerOptions, // Virtual scroller options. }	Custom loader template. This template can be used with virtualScroll.
dropdownicon	null	Custom dropdown trigger icon template.
clearicon	null	Custom clear icon template.
filtericon	null	Custom filter icon template.

Events #

Defines the custom events used by the component's emitters.

DropdownChangeEvent #

Custom change event.

name	type	description
originalEvent	Event	Browser event.
value	any	Selected option value

DropdownFilterEvent #

Custom filter event.

name	type	description
originalEvent	Event	Browser event.
filter	any	Filter value.

DropdownLazyLoadEvent #

Custom lazy load event.

name	type	description
first	number	Index of the first element in viewport.
last	number	Index of the last element in viewport.

Interfaces #

Defines the custom interfaces used by the module.

DropdownFilterOptions #

Filter callbacks of the dropdown.

name	type	description
filter	Function
reset	Function