fix(seo): Add a type for SEO data

Author: feloy

src/app/app.component.ts

@@ -6,7 +6,7 @@ import {
   RouterEvent
 } from '@angular/router';
 import { filter, map, mergeMap } from 'rxjs/operators';
-import { SeoService } from './services/seo.service';
+import { SeoService, SeoData } from './services/seo.service';
 
 interface Menu {
   title: string;
@@ -61,12 +61,9 @@ export class AppComponent implements OnInit {
           return route;
         }),
         filter(route => route.outlet === 'primary'),
-        mergeMap(route => route.data)
+        mergeMap(route => route.data),
+        filter((data: SeoData) => data.title !== undefined)
       )
-      .subscribe(data => {
-        if (data !== {}) {
-          this._seo.setHeaders(data.title || [], data.description || '');
-        }
-      });
+      .subscribe((data: SeoData) => this._seo.setHeaders(data));
   }
 }

src/app/operators/components/operator/operator.component.ts

@@ -39,12 +39,12 @@ export class OperatorComponent implements OnInit {
           this.operators.filter(
             (operator: OperatorDoc) => operator.name === name
           )[0] || this.notfound();
-        this._seo.setHeaders(
-          [this.operator.name, this.operator.operatorType],
-          this.operator.shortDescription
+        this._seo.setHeaders({
+          title: [this.operator.name, this.operator.operatorType],
+          description: this.operator.shortDescription
             ? this.operator.shortDescription.description
             : ''
-        );
+        });
       });
   }
 

src/app/services/seo.service.ts

@@ -1,18 +1,23 @@
 import { Injectable } from '@angular/core';
 import { Title, Meta } from '@angular/platform-browser';
 
+export interface SeoData {
+  title?: string[];
+  description?: string;
+}
+
 @Injectable()
 export class SeoService {
   // This part is happended at the end of head>title
   private siteTitle = 'RxJS Documentation';
 
   constructor(private _title: Title, private _meta: Meta) {}
 
-  public setHeaders(titleParts: string[], description: string) {
-    this._title.setTitle([...titleParts, this.siteTitle].join(' \u2022 '));
-    if (description && description.length) {
+  public setHeaders(data: SeoData) {
+    this._title.setTitle([...data.title, this.siteTitle].join(' \u2022 '));
+    if (data.description && data.description.length) {
       this._meta.updateTag({
-        content: description,
+        content: data.description,
         name: 'description'
       });
     }