Highlight filtering in Angular Drop down list component

27 Sep 20234 minutes to read

By using the highlightSearch method, you can highlight the matched character in DropDownList filtering.

The following example demonstrates about how to highlight the matched character in filtering.

app.component.ts

import { Component } from '@angular/core';
import { Query, DataManager, ODataV4Adaptor } from '@syncfusion/ej2-data';
import { FilteringEventArgs, highlightSearch } from '@syncfusion/ej2-dropdowns';

@Component({
    selector: 'app-root',
    // specifies the template string for the DropDownList component with change event
    template: `<ejs-dropdownlist id='ddlelement' [dataSource]='data' [query]='query' [fields]='fields' [placeholder]='text' [allowFiltering]='true' [sortOrder]='sorting' (filtering)='onFiltering($event)'></ejs-dropdownlist>`
})
export class AppComponent {
        constructor() {
        }
    //bind the DataManager instance to dataSource property
    public data: DataManager = new DataManager({
        url: 'https://services.odata.org/V4/Northwind/Northwind.svc/',
        adaptor: new ODataV4Adaptor,
        crossDomain: true
    });
    public query: Query = new Query().from('Customers').select(['ContactName', 'CustomerID']).take(6);
    // maps the appropriate column to fields property
    public fields: Object = {
        text: 'ContactName', value: 'CustomerID', itemCreated: (e: any) => {
            highlightSearch(e.item, (this as any).queryString, true, 'StartsWith');
        }
    };
    // set the placeholder to the DropDownList input
    public text: string = "Select a customer";
    //sort the result items
    public sorting: string = 'Ascending';
    public queryString?: string;
    //Bind the filter event
    public onFiltering: any = (e: FilteringEventArgs) => {
        // take text for highlight the character in list items.
        this.queryString = e.text;
        let query: Query = new Query().from('Customers').select(['ContactName', 'CustomerID']);
        query = (e.text !== '') ? query.where('ContactName', 'startswith', e.text, true) : query;
        e.updateData(this.data, query);
    };
}

app.module.ts

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { AppComponent } from './app.component';
import { DropDownListModule } from '@syncfusion/ej2-angular-dropdowns';
import { ButtonModule } from '@syncfusion/ej2-angular-buttons';
/**
 * Module
 */
@NgModule({
    imports: [
        BrowserModule,FormsModule, ReactiveFormsModule, DropDownListModule, ButtonModule
    ],
    declarations: [AppComponent],
    bootstrap: [AppComponent]
})
export class AppModule { }

main.ts

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppModule } from './app.module';

import 'zone.js';
enableProdMode();
platformBrowserDynamic().bootstrapModule(AppModule);