Angular 4 - Update Meta tags dynamically for Facebook (Open graph)

How do we add/update meta tags dynamically so that they get picked by Facebook/Whatsapp share dialog?

I upgraded my angular 2 application to angular 4 in order to use Meta service to add/update meta tags dynamically once we get the data in component from API.

So far in my component, I have

this.metaService.updateTag({ property: 'og:title', content: pageTitle });
this.metaService.updateTag({ property: 'og:url', 'www.domain.com/page' });
this.metaService.updateTag({ property: 'og:image', content: coverUrl, itemprop: 'image' });
this.metaService.updateTag({ property: 'og:image:url', content: coverUrl, itemprop: 'image' });
this.metaService.updateTag({ property: 'og:image:type', content: 'image/png' });

I am using updateTag because I have added static tags already with default values. This code successfully updates the meta tags values when I inspect them.

I know it makes sense that Facebook/Whatsapp debugger tools doesn't execute any javascript so it won't ever probably be executed in their environment.

I'm using https://developers.facebook.com/tools/debug/ and it always picks up the default tag values which makes sense.

My question is, what is the way around so that Facebook/Whatsapp picks up the updated tag values dynamically? I'm using Angular 4 and loading all data via API calls so its not possible to get any sort of data before the page loads and script is executed.

Open Graph OG Tags must be within the sourcecode!

You need to provide a static html page containing the the open graph tags like og:image og:title and og:description in the html sourcecode, since facebook, twitter and co a just scraping the plain html without rendering it through javascript. Angular dynamically updates the dom through js and therefore the crawlers just get the initial index.html.

There are several ways to serve an html containing open graph tags ans solve your issue:

• Serverside rendering with angular universal
• use an proxy rendering your page
• overwriting index.html on the fly replacing og tags
• serving static html pages (not sure if this is supported by angular)

I guess you already use something like ngx-meta to add og tags?

Angular Universal - Server Side Rendering with meta tags in Angular 2/3/4/5

I guess server-side rendering is the most appropriate way to solve your issue. For this you can host a node server or use eg. AWS Lambda. The disadvantage with this, your app has to be actively hosted and can not be served statically anymore. Anyways this seems to be the best way since it also is improves SEO. Angular Universal is the term to search for:

• Angular Universal
• Angular Universal Starter Boilerplate
• Angular Universal PWA with serverside rendering serverless with aws lambda boilerplate

Angular Universal Prerendering on build

You can also prerender specific routes on the build process and serve angular as a static app with multiple prerendered index.html files. If you only have few static routes this works perfectly fine. Thinking of more generic routes with dynamic parts, this is not the solution. Go for server side rendering. The angular universal boilerplate also contains an example for this. See prerender.ts

Alternative Solutions

Prerendering Angular with a proxy to provide OG Tags

If you like to avoid implementing serverside / prerendering during the build process (setting up angular universal sometimes is a pain for not good structured apps.) you can try to use a proxy service prerendering you page. Take a look at eg. prerender.io.

Overwriting index.html

Redirect all requests to an script which overwrites the og:tags. Eg. Using PHP and .htaccess to overwrite og tags this is possible with modern environments too. Eg. you could use cloudfront / api gateway and a lambda function. Have not seen an example for this though.

Facebook Cache and Open Graph Debugging

Be aware that caches may still have cached the open graph information from their first crawl. Ensure your source code is the lastest and all caches, reverse proxies like nginxx, cloudfront are cleared.

Use Facebook Debugger to debug open graph caches and clear facebook opengraph cache

As of 2018/19 and if your main goal is SEO (or probably more "SMO" - Social Media Optimization - since the Googlebot does a great job at evaluating JavaScript but most social media bots don't) your SSR solution of choice maybe should not be Angular Universal but something which uses a headless browser.

This would fall under the "proxy" categorie from Manuel's answer but since I haven't seen them posted yet here two (and a half) really great solutions:

Rendertron

This one is maintained by the Google Chrome team itself and is simply a great endpoint for rendering your app and returning it.

Rendora

Much like Rendertron but this one has the middleware (i.e. where and how you decide which requests get rendered and which not) already built in and also comes with some more advanced but handy features like caching. Therefore it is really very close to it's "zero configuration needed" goal and even easier to set up than Rendertron.

Puppeteer

Again maintained by the Google Chrome team (and actually used by Rendertron) Puppeteer provides a node based high level API for headless Chrome. So if the previous projects are two stiff for you, you probably will be able to implement a fitting solution with Puppeteer but obviously it will be more work than just using Rendertron or Rendora.

Compared to Angular Universal this solutions have the huge advantage that your app project can stay completely agnostic towards the used SSR tool (it could even be using any other technology besides Angular). And this obviously not only gives you more flexibility for your own code but for your package choices as well since you don't have to worry if they are Angular Universal compatible or not. Their disadvantage could be a little performance overhead but if you just target bots this probably will not matter. And if you use Rendora's caching this may not even be true and you may actually have a performance increase. However if that could be comparable to the performance increase you can achieve with Angular Universal I don't know. But keep in mind that when we talk about performance increase from SSR we always only talk about the time to first page loads anyways. So typically the importance of this is not too high since your users will interact a lot more with your app after its first load. If they don't and you have mainly anonymous users which just check one page and then leave you probably wouldn't be building a PWA but a classical web page in the first place...

tl;dr just check out Rendora and Rendertron, they may be what you are looking for and get you there very easy and fast.

Try this (using fb API: v2.12):

FB.ui({
  method: 'share_open_graph',
  action_type: 'og.shares',
  action_properties: JSON.stringify({
    object : {
      'og:url': 'url', // your url to share
      'og:title': 'title',
      'og:site_name':'site_name',
      'og:description':'description',
      'og:image': 'image Url',//
      'og:image:width':'250',//size of image in pixel
      'og:image:height':'257'
    }
  })
}, function(response){
  console.log("response is ",response);
});