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Type | Treat 2021 - Day 1

Orta on October 26, 2021

Type or Treat Challenges Today we're starting up our second year of Type | Treat (or "Type or Treat".) We will be presenting some "spook...

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Nick Taylor • Oct 27 '21

Hi @orta ! No biggie, but if you want, you can create a series on dev.to for the type | treat challenge. You can create a series in the editor by clicking on the cog icon at the bottom near the publish/save draft button. 😎

Orta • Oct 27 '21

Ah, I have to change my settings from markdown only to rich to see this cog! Took a while to find, will update - thanks!

Orta • Oct 27 '21

Ah, I can't seem to edit the posts and switch them into the rich edit mode - so I don't think I can switch this into a series, shame - it's a good feature

Nick Taylor • Oct 27 '21

You can add a series in the v1 editor as well. Just add a series field to the frontmatter. e.g.

---
title: test
published: true
description:  
series: type | treat
tags: 
//cover_image: https://direct_url_to_image.jpg
---

A test

brunnerh • Oct 28 '21

Not fan of the suggested solution to the intermediate problem. It creates unnecessarily tight coupling between all the functions, which defeats the purpose of having them exist separately in the first place.

I would make the functions generic and only require the minimal used interface (the estimate property).

Solution

(The { estimate: number } could of course be extracted.)

JayCruz • Oct 26 '21

I figured out the beginner Day 1 Solution but don't fully understand how the typeof trick on the song param works.

tusharar091 • Oct 27 '21

Basically if you don't assert array 'as const' , typescript will infer it as a string array meaning any string whether it is a song from the playlist or not will be perfectly valid. When you use "type of playlist[number]" to define the type of the song param, that means you have a created your own type which will only limit the values to the "songs which are part of your playlist array", so if you pass any other string or make a typo , compiler will through you an error.

e.g :-
const keywords=['var','let','const'] as const;

function getKeyword(keyword:string){
return keywords.find(a=>a===keyword);
}
getKeyword('var') //Valid
getKeyword('let') //Valid
getKeyword('cout') //Returns undefined.

To limit keyword:string parameter to include only 'var|let|const' as values you can use typeof keywords[number] and modify your code like this.

function getKeyword(keyword:typeof keywords[number]){
return keywords.find(a=>a===keyword);
}
getKeyword('var') //Valid
getKeyword('let') //Valid
getKeyword('cout') //TS throws compilation error.