This post will teach us how to use an Angular application to design a custom search filter pipe.

Required conditions
Basic familiarity with Angular 2 or later; installation of Node and NPM; Visual Studio Code; Bootstrap (Optional)
The command to create an Angular project is as follows.
ng new angapp

Now install Bootstrap by using the following command.
npm install bootstrap --save

Now open the styles.css file and add Bootstrap file reference. To add a reference in the styles.css file add this line.
@import '~bootstrap/dist/css/bootstrap.min.css';

Create Search Filter Pipe
Now create a custom pipe by using the following command.
ng generate pipe searchfilter

Now open searchfilter.pipe.ts file and add following code.
import { Pipe, PipeTransform } from '@angular/core';

@Pipe({ name: 'searchFilter' })
export class FilterPipe implements PipeTransform {
   transform(value: any, args?: any): any {
    if (!value) return null;
    if (!args) return value;

    args = args.toLowerCase();
    debugger;
    return value.filter(function(item:any) {
      return JSON.stringify(item)
        .toLowerCase()
        .includes(args);
    });
  }
}

Now import this pipe into the app module.Add following code in app.module.ts.
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { HttpClientModule } from '@angular/common/http';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';
import { FilterPipe } from './searchfilter.pipe';
import { SearchlistComponent } from './searchlist/searchlist.component';
@NgModule({
  declarations: [
    AppComponent,FilterPipe,SearchlistComponent
  ],
  imports: [
    BrowserModule,
    AppRoutingModule,
    FormsModule,
    HttpClientModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

Now create a new component by using the following command.
ng g c searchlist

Now open searchlist.component.html file and add the following code.
<div class="container">
    <div class="card">
        <div class="form-group">
            <label for="search-text">Search Text</label>
            <input type="email" class="form-control" id="search-text" aria-describedby="search-text"
                [(ngModel)]="searchText" placeholder="Enter text to search" autofocus>
        </div>
        <ul class="list-group list-group-flush">
            <li class="list-group-item" *ngFor="let user of userlist | searchFilter: searchText">
                {{user.firstName}}
            </li>
        </ul>
    </div>
</div>

Now open searchlist.component.ts file and add the following code.
import { Component, OnInit } from '@angular/core';
import { HttpClient } from '@angular/common/http';
@Component({
  selector: 'app-searchlist',
  templateUrl: './searchlist.component.html',
  styleUrls: ['./searchlist.component.css']
})
export class SearchlistComponent implements OnInit {
  data: any;
  searchText = '';
  userlist: any;
  constructor(private httpclient: HttpClient) {
  }
  ngOnInit(): void {
    this.httpclient.get('https://dummyjson.com/users').subscribe((res: any) => {
      this.data = res
      this.userlist = this.data.users;
      console.log(this.userlist);
    })
  }
}

Now open app.component.html file and add the following code.
<div class="container" style="margin-top:10px;margin-bottom: 24px;">
  <div class="col-sm-12 btn btn-info">
    Create Custom Search filter pipe in Angular Application
  </div>
</div>
<app-searchlist></app-searchlist>

Now run the application using npm start and check the result.

Now type some text into the box and run a search.