js method chaining (it’s beautiful)

One of the best things you can do in js, is chain methods. more info here but here are some examples:

example 1: string

let prependName = fullpath
      .replace(filename, "??filename")
      .replace(basedDir, "??basedDir")
      .split(slash)
      .filter(part => !["??basedDir", "??filename"].includes(part))
      .join(pslash)

first replaces some stuff, then splits (now we have an array), filter the array and join back into a string. This one was pretty easy, but this feature is really powerful. Let's see another example:

example 2: grabbing and filtering links from site

[...document.querySelectorAll("a[href]")]
  .map(i => i.href)
  .filter(i => i.startsWith("https://videoportal.joj.sk/prazdniny/epizoda"))
  .join("\n")

this particular snippet lets you grab all links to episodes of the TV series 'Prázdniny' from joj.sk.
you could use the same approach to grab any anime/tvshow/other video links from a site.

bonus tip:
save these links into batch.txt, install yt-dlp,
run yt-dlp -a batch.txt --remux-video mp4
you've sucessfully downloaded all of the links

example 3: array (more complex)

you don't need to completely understand the following example, just see that you can chain a lot of powerful transformations together like this.

certs = initialArray.map(result => {
  const country = result["iso_3166_1"]
  const certifications = result["release_dates"]
  return { country, certs: [...new Set([ ...certifications.map(c => c.certification) ])].filter(c => c !== "") }
})
	.filter((cert) => cert.certs.length > 0 )
	.map(({country, certs}) => ({country, cert: certs[0].trim().replaceAll(" ", "") }))

source

1. initialArray is mapped =, transforming an array of objects into something simpler ({country: string, certs: string[]})
   1. the stuff it returns first spreads an array into a set and then the set back into an array. This is an effective method of removing duplicates
   2. .filter(c => c !== "") just removes empty elements
2. all countries which don't have any certifications are filtered out
3. cast certs[0] to cert

one last caveat

• avoid doing unnecessary array iterations with map, filter, reduce etc.
• instead of, for example, array.map(i => i).map(i => i).map(i => i).map(i => i), try to combine it into one .map(...) where possible.
• different types of mutations after each other, or repeated mutation that depend on previous ones are fine 👍