Code Snippets

Here are some code snippets you might find useful. I leave them there when they don't deserve a library on their own.

You can find more on my Twitter account.

URL query string from object#

TypeScript
 
Browser
 
Node.js

Create a URL with escaped query string arguments from an object, without any dependencies:

export function url(base: string, args: object): string {
  const url = new URL(base)
  Object.entries(args).forEach(([key, value]) => {
    url.searchParams.set(key, value)
  })
  return url.toString()
}

// Example usage:
url('https://accounts.spotify.com/authorize', {
  client_id: process.env.SPOTIFY_CLIENT_ID,
  redirect_uri: 'http://localhost:12345',
  response_type: 'token'
})
// -> https://accounts.spotify.com/authorize?client_id=foobar&redirect_uri=http%3A%2F%2Flocalhost%3A12345&response_type=token

Browser support for URLSearchParams (used in url.searchParams):

Data on support for the urlsearchparams feature across the major browsers from caniuse.com


Interface type filtering#

TypeScript
 
Metaprogramming

Get the keys of an object for which the value is of a given type:

export type FilterKeys<Source, Condition> = {
  [key in keyof Source]: Source[key] extends Condition ? key : never
}[keyof Source]

// Example usage:
interface User {
  firstName: string
  lastName: string
  age: number
}

type UserStringKeys = FilterKeys<User, string> // 'firstName' | 'lastName'

Make RFCs easier to read#

Browser
 
CSS

Ahh RFCs, the core documentation of the Internet, so useful at times, but still visually anchored in the 1980s. Let's make them look nicer with a bit of CSS, shall we ?

Copy and paste this in your console when viewing an RFC:

document
  .querySelector('.content')
  .setAttribute(
    'style',
    'margin:0 auto;font-size:16px;line-height:1.4;color:#333'
  )