• Description
• Getting started
• Examples
• Customization
• API
  • NgxVirtualSelectFieldComponent
  • NgxVirtualSelectFieldOptionComponent
  • NgxVirtualSelectFieldOptionSelectionChangeEvent
  • NgxVirtualSelectFieldTriggerComponent
  • NgxVirtualSelectFieldOptionForDirective
  • NgxVirtualSelectFieldOptionModel
  • NGX_VIRTUAL_SELECT_FIELD_CONFIG
  • NgxVirtualSelectFieldConfig
  • CSS variables

This package replicates the Angular Material Select component with virtual scroll capabilities with help of cdk-virtual-scroll. It provides most major features of the original Angular Material Select component. The goal of this package is to provide similar api and features as the original Angular Material Select component but with virtual scroll capabilities. One major difference is that this package does not support option groups at the moment. Also, this requires own structural directive to be used for options in order to provide virtual scroll capabilities and custom template.

Features:

• Virtual scroll
• Multi select
• Single select
• Integrates with Angular Material Form Field
• Custom trigger template
• Custom option template
• Keyboard navigation and shortcuts
• Theming trough css variables

Not Supported Features for now:

• Animations
• Custom Error state mather
• Custom scroll strategy
• Accessibility
• Some additional input parameters and outputs
• Option groups

1. Install package

   npm install ngx-virtual-select-field

2. Import bundle into your component

   import { NgxVirtualSelectFieldBundle } from 'ngx-virtual-select-field';
   ...
   @Component({
     imports: [
       NgxVirtualSelectFieldBundle,
       ...
     ],
     ...
   })

3. Create options collection in component. Options collection should be an array of objects with value and label properties. Optionally, you can add disabled property to disable specific options and getLabel() fot type ahead search.

   ...
   protected options: NgxVirtualSelectFieldOptionModel<number>[]
   
   constructor() {
     this.options = new Array(100000)
       .fill(null)
       .map((_, index) => ({
         value: index,
         label: `${index} Option`,
         disabled: index % 5 === 0,
       }));
   }

4. Setup template markup. ngxVirtualSelectFieldOptionFor directive should be user to pass options collection to the component and provide custom option template.

   <mat-form-field>
     <mat-label>Virtual Select Field Example</mat-label>
     <ngx-virtual-select-field [value]="value">
       <ngx-virtual-select-field-option *ngxVirtualSelectFieldOptionFor="let option of options" [value]="option.value"> {{ option.label }} </ngx-virtual-select-field-option>
     </ngx-virtual-select-field>
   </mat-form-field>

5. Include theme styles. You can define your own theme with help of css variables or inherit from material theme.

   @use 'ngx-virtual-select-field/theme' as theme;
   
   @include theme.inherit-material-theme(); // this will inherit css variables from material theme
   
   // or
   
   @include theme.create-default-theme(); // this will create basic dark theme

Basic setup with value input and output binding

<mat-form-field>
  <mat-label>Example</mat-label>
  <ngx-virtual-select-field [value]="value" (valueChange)="onValueChange($event)">
    <ngx-virtual-select-field-option *ngxVirtualSelectFieldOptionFor="let option of options" [value]="option.value"> {{ option.label }} </ngx-virtual-select-field-option>
  </ngx-virtual-select-field>
</mat-form-field>

Form control integration

<mat-form-field>
  <mat-label>Form Control Example</mat-label>
  <ngx-virtual-select-field [formControl]="formControl">
    <ngx-virtual-select-field-option *ngxVirtualSelectFieldOptionFor="let option of options" [value]="option.value"> {{ option.label }} </ngx-virtual-select-field-option>
  </ngx-virtual-select-field>
</mat-form-field>

Multi select

<mat-form-field>
  <mat-label>Multi Select Example</mat-label>
  <ngx-virtual-select-field [value]="value" multiple (valueChange)="onValueChange($event)">
    <ngx-virtual-select-field-option *ngxVirtualSelectFieldOptionFor="let option of options" [value]="option.value"> {{ option.label }} </ngx-virtual-select-field-option>
  </ngx-virtual-select-field>
</mat-form-field>

Custom trigger template

<mat-form-field class="field">
  <mat-label>Custom Trigger Example</mat-label>
  <ngx-virtual-select-field multiple [(value)]="value">
    <ngx-virtual-select-field-trigger> {{ value.length }} selected </ngx-virtual-select-field-trigger>

    <ngx-virtual-select-field-option *ngxVirtualSelectFieldOptionFor="let option of options" [value]="option.value"> {{ option.label }} </ngx-virtual-select-field-option>
  </ngx-virtual-select-field>
</mat-form-field>

Components supports custom templates for trigger and option elements. You can use ngx-virtual-select-field-trigger and ngx-virtual-select-field-option components to define custom templates.

There are number of input parameters available to specify specific behavior of the component.

Injection tokens might be used to customize all component instances

All styles are defined with css variables, so you can easily override them in your own styles.

See more in API section below.

selector: ngx-virtual-select-field
Component to define select field

selector: ngx-virtual-select-field-option
Component to define option element

Interface to define option selection change event contract
Properties:

selector: ngx-virtual-select-field-trigger
Directive to define custom trigger template

selector: *ngxVirtualSelectFieldOptionFor
Directive to define custom option template and iterate over options

Interface to define option model contract
Properties:

Injection token to define global configuration for all instances of the component Config see in NgxVirtualSelectFieldConfig interface

Interface to define global configuration contract Properties:

All styles are defined with css variables, so you can easily override them in your own styles. CSS variables for main component:

:root {
  --ngx-virtual-select-field-trigger-text-color: ...;
  --ngx-virtual-select-field-trigger-text-color--disabled: ...;
  --ngx-virtual-select-field-trigger-font-family: ...;
  --ngx-virtual-select-field-trigger-line-height: ...;
  --ngx-virtual-select-field-trigger-font-size: ...;
  --ngx-virtual-select-field-trigger-font-weight: ...;
  --ngx-virtual-select-field-trigger-letter-spacing: ...;

  --ngx-virtual-select-field-placeholder-text-color: ...;
  --ngx-virtual-select-field-placeholder-transition: ...;

  --ngx-virtual-select-field-arrow-size: ...;
  --ngx-virtual-select-field-arrow-color--enabled: ...;
  --ngx-virtual-select-field-arrow-color--focused: ...;
  --ngx-virtual-select-field-arrow-color--invalid: ...;
  --ngx-virtual-select-field-arrow-color--disabled: ...;

  --ngx-virtual-select-field-panel-viewport-page-size: ...;
  --ngx-virtual-select-field-panel-background: ...;
  --ngx-virtual-select-field-panel-box-shadow: ...;
  --ngx-virtual-select-field-panel-option-height: ...;
}

CSS variables for option component:

:root {
  --ngx-virtual-select-field-option-color: ...;
  --ngx-virtual-select-field-option-font-family: ...;
  --ngx-virtual-select-field-option-line-height: ...;
  --ngx-virtual-select-field-option-font-size: ...;
  --ngx-virtual-select-field-option-letter-spacing: ...;
  --ngx-virtual-select-field-option-font-weight: ...;

  --ngx-virtual-select-field-option-selected-state-label-text-color: ...;
  --ngx-virtual-select-field-option-background-color--active: ...;
  --ngx-virtual-select-field-option-background-color--hover: ...;
  --ngx-virtual-select-field-option-background-color--selected: ...;

  --ngx-virtual-select-field-option-disabled-state-opacity: ...;
  --ngx-virtual-select-field-option-gap: ...;
  --ngx-virtual-select-field-option-padding: ...;
  --ngx-virtual-select-field-option-item-height: ...;
}