Commonly use es6 - in angular typescript for list. filter,map,find,findIndex

import { Component } from '@angular/core';

@Component({
  selector: 'friday-app',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'Manage your Friday Activity';
  private fridayActivityList: FridayActivity[] = [];
  
  private fridayActivityListFiltered: FridayActivity[] = [];
  private fridayActivityListMapped: FridayActivity[] = [];
  private fridayActivityListItem:  FridayActivity;
  private fridayActivityListIndex:  number;
    

  ngOnInit(): void {
    this.initializeList();
  }
 
  initializeList(): void {

    const drinkingActivity = new FridayActivity(1, 'Pub and Bar Gathering');
    const movieActivity = new FridayActivity(2, 'Movie Night');
    const diningActivity = new FridayActivity(3, 'Romantic Dining');

    this.fridayActivityList.push(drinkingActivity);
    this.fridayActivityList.push(movieActivity);
    this.fridayActivityList.push(diningActivity);
    
    this.fridayActivityListFiltered = this.doFilter('Movie');
    this.fridayActivityListIndex = this.doFindIndex('Movie');
    this.fridayActivityListItem =this.doFindItem('Movie');
    this.fridayActivityListMapped = this.doMap('Movie');
  } 
  
  doFilter(_keyword){  
    return this.fridayActivityList.filter( (itemObject)=> {
      const keyword =`${itemObject.activityName}`;
      return keyword.match(_keyword) ;
    });
  }
  doMap(_keyword){  
    return this.fridayActivityList.map( (itemObject)=> {
      const reference =`${itemObject.id} - ${itemObject.activityName}`;
      return {id:itemObject.id, activity:itemObject.activityName,reference:reference } 
    });
  }


  doFindItem(_keyword){ 
    return this.fridayActivityList.find( (itemObject)=> {
      const keyword =`${itemObject.activityName}`;
      return keyword.match(_keyword) ;
    });
  }
  doFindIndex(_keyword){
    
    return this.fridayActivityList.findIndex( (itemObject)=> {
      const keyword =`${itemObject.activityName}`;
      return keyword.match(_keyword) ;
    });
  }
}

class FridayActivity {

  constructor(id: number, activityName: string) {
    this.id = id;
    this.activityName = activityName;
  }


  private id: number;
  private activityName: string;

}

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule }   from '@angular/forms';
import { HttpModule }    from '@angular/http';
 
 

import { AppComponent } from './app.component'; 

@NgModule({
  imports: [
    BrowserModule,
    FormsModule,
    HttpModule 
  ],
  declarations: [
    AppComponent 
  ],
  providers: [   ],
  bootstrap: [ AppComponent ]
})
export class AppModule { }

h1 {
  font-size: 1.2em;
  color: #999;
  margin-bottom: 0;
}
h2 {
  font-size: 2em;
  margin-top: 0;
  padding-top: 0;
}
nav a {
  padding: 5px 10px;
  text-decoration: none;
  margin-top: 10px;
  display: inline-block;
  background-color: #eee;
  border-radius: 4px;
}
nav a:visited, a:link {
  color: #607D8B;
}
nav a:hover {
  color: #039be5;
  background-color: #CFD8DC;
}
nav a.active {
  color: #039be5;
}
.hidden{
  display:none !important;
}

.float-right{
   float:right;
 }
 code{
   background:rgba(255,255,255,.6);
 }

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';

import { AppModule } from './app/app.module';

platformBrowserDynamic().bootstrapModule(AppModule);

/* Master Styles */
h1 {
  color: #369;
  font-family: Arial, Helvetica, sans-serif;
  font-size: 250%;
}
h2, h3 {
  color: #444;
  font-family: Arial, Helvetica, sans-serif;
  font-weight: lighter;
}
body {
  margin: 2em;
}
body, input[text], button {
  color: #888;
  font-family: Cambria, Georgia;
}
a {
  cursor: pointer;
  cursor: hand;
}
button {
  font-family: Arial;
  background-color: #eee;
  border: none;
  padding: 5px 10px;
  border-radius: 4px;
  cursor: pointer;
  cursor: hand;
}
button:hover {
  background-color: #cfd8dc;
}
button:disabled {
  background-color: #eee;
  color: #aaa;
  cursor: auto;
}

/* Navigation link styles */
nav a {
  padding: 5px 10px;
  text-decoration: none;
  margin-right: 10px;
  margin-top: 10px;
  display: inline-block;
  background-color: #eee;
  border-radius: 4px;
}
nav a:visited, a:link {
  color: #607D8B;
}
nav a:hover {
  color: #039be5;
  background-color: #CFD8DC;
}
nav a.active {
  color: #039be5;
}

/* everywhere else */
* {
  font-family: Arial, Helvetica, sans-serif;
}


/*
Copyright 2017 Google Inc. All Rights Reserved.
Use of this source code is governed by an MIT-style license that
can be found in the LICENSE file at http://angular.io/license
*/

<!DOCTYPE html>
<html>
  <head>
    <script>document.write('<base href="' + document.location + '" />');</script>
    <title>Angular Tour of Heroes</title>
    <meta name="viewport" content="width=device-width, initial-scale=1">

    <link rel="stylesheet" href="styles.css">

    <!-- Polyfills -->
    <script src="https://unpkg.com/core-js/client/shim.min.js"></script>

    <script src="https://unpkg.com/zone.js@0.7.4?main=browser"></script>
    <script src="https://unpkg.com/systemjs@0.19.39/dist/system.src.js"></script>

    <script src="systemjs.config.js"></script>
    <script>
      System.import('main.js').catch(function(err){ console.error(err); });
    </script>
  </head>

  <body>
    <friday-app>Loading...</friday-app>
  </body>
</html>

/**
 * WEB ANGULAR VERSION
 * (based on systemjs.config.js in angular.io)
 * System configuration for Angular samples
 * Adjust as necessary for your application needs.
 */
(function (global) {
  System.config({
    // DEMO ONLY! REAL CODE SHOULD NOT TRANSPILE IN THE BROWSER
    transpiler: 'ts',
    typescriptOptions: {
      // Copy of compiler options in standard tsconfig.json
      "target": "es5",
      "module": "commonjs",
      "moduleResolution": "node",
      "sourceMap": true,
      "emitDecoratorMetadata": true,
      "experimentalDecorators": true,
      "lib": ["es2015", "dom"],
      "noImplicitAny": true,
      "suppressImplicitAnyIndexErrors": true
    },
    meta: {
      'typescript': {
        "exports": "ts"
      }
    },
    paths: {
      // paths serve as alias
      'npm:': 'https://unpkg.com/'
    },
    // map tells the System loader where to look for things
    map: {
      // our app is within the app folder
      'app': 'app',

      // angular bundles
      '@angular/animations': 'npm:@angular/animations/bundles/animations.umd.js',
      '@angular/animations/browser': 'npm:@angular/animations/bundles/animations-browser.umd.js',
      '@angular/core': 'npm:@angular/core/bundles/core.umd.js',
      '@angular/common': 'npm:@angular/common/bundles/common.umd.js',
      '@angular/compiler': 'npm:@angular/compiler/bundles/compiler.umd.js',
      '@angular/platform-browser': 'npm:@angular/platform-browser/bundles/platform-browser.umd.js',
      '@angular/platform-browser/animations': 'npm:@angular/platform-browser/bundles/platform-browser-animations.umd.js',
      '@angular/platform-browser-dynamic': 'npm:@angular/platform-browser-dynamic/bundles/platform-browser-dynamic.umd.js',
      '@angular/http': 'npm:@angular/http/bundles/http.umd.js',
      '@angular/router': 'npm:@angular/router/bundles/router.umd.js',
      '@angular/router/upgrade': 'npm:@angular/router/bundles/router-upgrade.umd.js',
      '@angular/forms': 'npm:@angular/forms/bundles/forms.umd.js',
      '@angular/upgrade': 'npm:@angular/upgrade/bundles/upgrade.umd.js',
      '@angular/upgrade/static': 'npm:@angular/upgrade/bundles/upgrade-static.umd.js',

      // other libraries
      'rxjs':                      'npm:rxjs@5.0.1',
      'angular-in-memory-web-api': 'npm:angular-in-memory-web-api/bundles/in-memory-web-api.umd.js',
      'ts':                        'npm:plugin-typescript@5.2.7/lib/plugin.js',
      'typescript':                'npm:typescript@2.3.2/lib/typescript.js',

    },
    // packages tells the System loader how to load when no filename and/or no extension
    packages: {
      app: {
        main: './main.ts',
        defaultExtension: 'ts',
        meta: {
          './*.ts': {
            loader: 'systemjs-angular-loader.js'
          }
        }
      },
      rxjs: {
        defaultExtension: 'js'
      }
    }
  });

})(this);

/*
Copyright 2016 Google Inc. All Rights Reserved.
Use of this source code is governed by an MIT-style license that
can be found in the LICENSE file at http://angular.io/license
*/

var templateUrlRegex = /templateUrl\s*:(\s*['"`](.*?)['"`]\s*)/gm;
var stylesRegex = /styleUrls *:(\s*\[[^\]]*?\])/g;
var stringRegex = /(['`"])((?:[^\\]\\\1|.)*?)\1/g;

module.exports.translate = function(load){
  if (load.source.indexOf('moduleId') != -1) return load;

  var url = document.createElement('a');
  url.href = load.address;

  var basePathParts = url.pathname.split('/');

  basePathParts.pop();
  var basePath = basePathParts.join('/');

  var baseHref = document.createElement('a');
  baseHref.href = this.baseURL;
  baseHref = baseHref.pathname;

  if (!baseHref.startsWith('/base/')) { // it is not karma
    basePath = basePath.replace(baseHref, '');
  }

  load.source = load.source
    .replace(templateUrlRegex, function(match, quote, url){
      var resolvedUrl = url;

      if (url.startsWith('.')) {
        resolvedUrl = basePath + url.substr(1);
      }

      return 'templateUrl: "' + resolvedUrl + '"';
    })
    .replace(stylesRegex, function(match, relativeUrls) {
      var urls = [];

      while ((match = stringRegex.exec(relativeUrls)) !== null) {
        if (match[2].startsWith('.')) {
          urls.push('"' + basePath + match[2].substr(1) + '"');
        } else {
          urls.push('"' + match[2] + '"');
        }
      }

      return "styleUrls: [" + urls.join(', ') + "]";
    });

  return load;
};

<h1> {{title }}</h1>


<p>Here we will use es6 to transform lists.</p>

<p>Night is young on friday night..So , we have a list of items to do...</p>
 

<hr>
<div>
    <ol>
        <li *ngFor="let activity of fridayActivityList">
            <a> {{activity.activityName }}</a>
        </li>
    </ol>

</div>

<pre>
<code>
 {{fridayActivityList |json }}
</code>
</pre>

<hr>
<p>Scenario 1: Now we kinda wanna only watch and filter keyword movie, how do we do it?</p>


<ol>
    <li *ngFor="let activity of fridayActivityListFiltered">
        <a> {{activity.activityName }}</a>
    </li>
</ol>

<pre>
<code>
 {{fridayActivityListFiltered |json }}
</code>
</pre>


<p> Answer:</p>
<pre>
<code>
 {{"   
      list.filter(  
            (itemObj)=>{return  itemObj.activityName == 'Movie'}
      )
 
 " }}
</code>
</pre>


<hr>

<p>Scenario 2: Now given a keyword or identfier, we wanna know this particular movie's ordering computer index in the list, how
    do we do it?</p>

<a> index= {{fridayActivityListIndex }} </a>


<p> Answer:</p>
<pre>
<code>
 {{"   
      list.findIdex(  
            (itemObj)=>{ return itemObj.activityName == 'Movie'}
      )
 
 " }}
</code>
</pre>



<hr>
<p>Scenario 3: Now given an identifier or keyword movie, how do we extract that particular item object information of movie
    from the list?</p>



<a> item={{fridayActivityListItem|json }}</a>


<p> Answer:</p>
<pre>
<code>
 {{"   
      list.find(  
            (itemObj)=>{ return itemObj.activityName == 'Movie'}
      )
 
 " }}
</code>
</pre>


<hr>

<p>Scenario 4: Now , we want to remap and transform our existing list format in each items.
How we do it?
</p>
<p>Before:
<a> {{fridayActivityList|json }}</a>
</p>
<p>After:  
<a> {{fridayActivityListMapped|json }}</a></p>


<p> Answer:</p>
<pre>
<code>
 {{"   
      list.map(  
            (itemObj)=>{
            const reference=`${itemObj.id}-${itemObj.activityName}`
            return {reference:reference, id:itemObj.id, activity:itemObj.activityName}  
      )
 
 " }}
</code>
</pre>

#Cheatsheet Es6 common list transformation
-map
-find
-filter
-findIndex

visit Angular-friday.com