tieppt/app.component.ts

## app.component.ts
import { Component } from '@angular/core';
import { SeoService } from 'path/to/seo.service';

@Component({
  selector: 'app-root',
  template: ``
})

export class AppComponent {
  constructor(seoService: SeoService) {
    seoService.setTitle('My awesome App Title!!!');
    seoService.setMetaDescription('My awesome Metadesciption');
    seoService.setMetaRobots('Index, Follow');
  }
}

## app.module.ts
import { NgModule } from '@angular/core';
import { SeoService } from 'path/to/seo.service';

@NgModule({
  providers: [
    // ... other service
    SeoService
  ]
})
export class AppModule {
}

## seo.service.ts
import { Injectable } from '@angular/core';
import { Title } from '@angular/platform-browser';
import { getDOM } from '@angular/platform-browser/src/dom/dom_adapter';

@Injectable()

export class SeoService {
 /**
  * Angular 2 Title Service
  */
  private titleService: Title;
 /**
  * <head> Element of the HTML document
  */
  private headElement: HTMLElement;
 /**
  * <head> Element of the HTML document
  */
  private metaDescription: HTMLElement;
 /**
  * <head> Element of the HTML document
  */
  private robots: HTMLElement;
  private DOM: any;

 /**
  * Inject the Angular 2 Title Service
  * @param titleService
  */
  constructor(titleService: Title){
    this.titleService = titleService;
    this.DOM = getDOM();

   /**
    * get the <head> Element
    * @type {any}
    */
    this.headElement = this.DOM.query('head');
    this.metaDescription = this.getOrCreateMetaElement('description');
    this.robots = this.getOrCreateMetaElement('robots');
  }

  public getTitle(): string {
    return this.titleService.getTitle();
  }

  public setTitle(newTitle: string) {
    this.titleService.setTitle(newTitle);
  }

  public getMetaDescription(): string {
    return this.metaDescription.getAttribute('content');
  }

  public setMetaDescription(description: string) {
    this.metaDescription.setAttribute('content', description);
  }

  public getMetaRobots(): string {
    return this.robots.getAttribute('content');
  }

  public setMetaRobots(robots: string) {
    this.robots.setAttribute('content', robots);
  }

   /**
    * get the HTML Element when it is in the markup, or create it.
    * @param name
    * @returns {HTMLElement}
    */
    private getOrCreateMetaElement(name: string): HTMLElement {
      let el: HTMLElement;
      el = this.DOM.query('meta[name=' + name + ']');
      if (el === null) {
        el = this.DOM.createElement('meta');
        el.setAttribute('name', name);
        this.headElement.appendChild(el);
      }
      return el;
    }

}
	import { Component } from '@angular/core';
	import { SeoService } from 'path/to/seo.service';

	@Component({
	selector: 'app-root',
	template: ``
	})

	export class AppComponent {
	constructor(seoService: SeoService) {
	seoService.setTitle('My awesome App Title!!!');
	seoService.setMetaDescription('My awesome Metadesciption');
	seoService.setMetaRobots('Index, Follow');
	}
	}
	import { NgModule } from '@angular/core';
	import { SeoService } from 'path/to/seo.service';

	@NgModule({
	providers: [
	// ... other service
	SeoService
	]
	})
	export class AppModule {
	}
	import { Injectable } from '@angular/core';
	import { Title } from '@angular/platform-browser';
	import { getDOM } from '@angular/platform-browser/src/dom/dom_adapter';

	@Injectable()

	export class SeoService {
	/**
	* Angular 2 Title Service
	*/
	private titleService: Title;
	/**
	* <head> Element of the HTML document
	*/
	private headElement: HTMLElement;
	/**
	* <head> Element of the HTML document
	*/
	private metaDescription: HTMLElement;
	/**
	* <head> Element of the HTML document
	*/
	private robots: HTMLElement;
	private DOM: any;

	/**
	* Inject the Angular 2 Title Service
	* @param titleService
	*/
	constructor(titleService: Title){
	this.titleService = titleService;
	this.DOM = getDOM();

	/**
	* get the <head> Element
	* @type {any}
	*/
	this.headElement = this.DOM.query('head');
	this.metaDescription = this.getOrCreateMetaElement('description');
	this.robots = this.getOrCreateMetaElement('robots');
	}

	public getTitle(): string {
	return this.titleService.getTitle();
	}

	public setTitle(newTitle: string) {
	this.titleService.setTitle(newTitle);
	}

	public getMetaDescription(): string {
	return this.metaDescription.getAttribute('content');
	}

	public setMetaDescription(description: string) {
	this.metaDescription.setAttribute('content', description);
	}

	public getMetaRobots(): string {
	return this.robots.getAttribute('content');
	}

	public setMetaRobots(robots: string) {
	this.robots.setAttribute('content', robots);
	}

	/**
	* get the HTML Element when it is in the markup, or create it.
	* @param name
	* @returns {HTMLElement}
	*/
	private getOrCreateMetaElement(name: string): HTMLElement {
	let el: HTMLElement;
	el = this.DOM.query('meta[name=' + name + ']');
	if (el === null) {
	el = this.DOM.createElement('meta');
	el.setAttribute('name', name);
	this.headElement.appendChild(el);
	}
	return el;
	}

	}