Quick tip: using flatMap() to extract data from a huge set without having to write a loop

I just created a massive dataset of all the AI generated metadata of the videos of the WeAreDeveloper World Congress" and I wanted to extract only the tags.

The dataset is a huge array with each item containing a description, generated title, an array of tags, the original and their title, like this:

{
  "description": "The talk begins with an introduction to Twilio…", 
  "generatedtitle: "Enhancing Developer Experience: Strategies… ",
  "tags": ["Twilio", "DeveloperExperience", "CognitiveJourney"],
  "title": "Diving into Developer Experience"
}

What I wanted was an alphabetical lost of all the tags in the whole dataset, and this is a one-liner if you use flatMap():

data.flatMap(d => d.tags);

You can sort them alphabetically with sort():

data.flatMap(d => d.tags).sort();

And you can de-dupe the data and only get unique tags when you use Set():

new Set(data.flatMap(d => d.tags).sort());

You can try this in this codepen.

Comments

[Ahmet Cetin]

Who will tell Christian that flatMap is actually a loop? :)