Golang : How to extract video or image files from html source code

There are times when I need to download a certain video that I watched using browser and I need to find the video's source file to download. The following is a simple example that demonstrate how to extract video or image files from HTML source code. Basically what it does is to grab the entire HTML data and filter out the file names with regular expression.

Here you go!

 package main

 import (
  "io/ioutil"
  "log"
  "net/http"
  "regexp"
 )

 func SearchForVideoLinks(url string) {

  log.Println("Parsing : ", url)

  // Request the HTML page.
  resp, err := http.Get(url)
  if err != nil {
 log.Fatal(err)
  }
  defer resp.Body.Close()
  if resp.StatusCode != 200 {
 log.Fatalf("Unable to get URL with status code error: %d %s", resp.StatusCode, resp.Status)
  }

  htmlData, err := ioutil.ReadAll(resp.Body)

  if err != nil {
 log.Fatal(err)
  }

  videoRegExp := regexp.MustCompile(`<video[^>]+`)
  sourceRegExp := regexp.MustCompile(`<source[^>]+`)

  videoMatchSlice := videoRegExp.FindAllStringSubmatch(string(htmlData), -1)
  sourceMatchSlice := sourceRegExp.FindAllStringSubmatch(string(htmlData), -1)

  for _, item := range videoMatchSlice {
 log.Println("Video found : ", item)
 for _, sourceItem := range sourceMatchSlice {
 log.Println("Source found : ", sourceItem)
 }
  }

 }

 func SearchForImageLinks(url string) {

  log.Println("Parsing : ", url)

  // Request the HTML page.
  resp, err := http.Get(url)
  if err != nil {
 log.Fatal(err)
  }
  defer resp.Body.Close()
  if resp.StatusCode != 200 {
 log.Fatalf("Unable to get URL with status code error: %d %s", resp.StatusCode, resp.Status)
  }

  htmlData, err := ioutil.ReadAll(resp.Body)

  if err != nil {
 log.Fatal(err)
  }

  imageRegExp := regexp.MustCompile(`<img[^>]+\bsrc=["']([^"']+)["']`)

  subMatchSlice := imageRegExp.FindAllStringSubmatch(string(htmlData), -1)
  for _, item := range subMatchSlice {
 log.Println("Image found : ", item[1])
  }

 }

 func main() {
  SearchForImageLinks("https://socketloop.com")
  SearchForImageLinks("https://golang.org")

  SearchForVideoLinks("https://cdpn.io/caraya/fullpage/FckCd")
 }

Sample output :

 2020/02/27 09:49:08 Parsing :  https://socketloop.com
 2020/02/27 09:49:09 Image found :  https://d1ohg4ss876yi2.cloudfront.net/socketloop-logo1.png
 2020/02/27 09:49:09 Image found :  //pixel.quantserve.com/pixel/p-31iz6hfFutd16.gif?labels=Domain.socketloop_com,DomainId.22847
 2020/02/27 09:49:09 Image found :  https://sb.scorecardresearch.com/p?c1=2&c2=20015427&cv=2.0&cj=1
 2020/02/27 09:49:09 Parsing :  https://golang.org
 2020/02/27 09:49:09 Image found :  /lib/godoc/images/go-logo-blue.svg
 2020/02/27 09:49:09 Image found :  /lib/godoc/images/cloud-download.svg
 2020/02/27 09:49:09 Image found :  /lib/godoc/images/footer-gopher.jpg
 2020/02/27 09:49:09 Parsing :  https://cdpn.io/caraya/fullpage/FckCd
 2020/02/27 09:49:10 Video found :  [<video id='video' controls=&quot;controls&quot; preload='none'
 width=&quot;600&quot; poster=&quot;http://media.w3.org/2010/05/sintel/poster.png&quot;]
 2020/02/27 09:49:10 Source found :  [<source id='mp4' src=&quot;http://media.w3.org/2010/05/sintel/trailer.mp4&quot; type='video/mp4'/]
 2020/02/27 09:49:10 Source found :  [<source id='webm' src=&quot;http://media.w3.org/2010/05/sintel/trailer.webm&quot; type='video/webm'/]
 2020/02/27 09:49:10 Source found :  [<source id='ogv' src=&quot;http://media.w3.org/2010/05/sintel/trailer.ogv&quot; type='video/ogg'/]