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Extract and Replace Links in HTML with JavaScript RegEx

For the Mail Merge project, I need to extract all the hyperlinks in the email message and append email tracking parameters to each of the links. The links can be either embedded in the HTML <a> tag or they can be mentioned in plain text like example.com – Gmail and other email clients are smart enough to replace such plain text website links into clickable hyperlinks.

I’m using RegEx to pull out these links from HTML / Text and then a simple JavaScript function to manipulate the link.

Replace Links inside HTML Tags

function updateLinksInHTML(html) {
    
  var regex = /href\s*=\s*(['"])(https?:\/\/.+?)\1/ig;   
  var link;
  
  while((link = regex.exec(html)) !== null) {
    html = html.replace(link[2], "https://ctrlq.org?redirect_to" + encodeURIComponent(link[2]));
  }
  
  return html;
  
}

Convert Plain Text into Links

Some text make contain links in plain text and this method would replace such links into clickable hyperlinks by adding the anchor tag.

function createTextLinks_(text) {
  
  return (text || "").replace(
    /([^\S]|^)(((https?\:\/\/)|(www\.))(\S+))/gi,
    function(match, space, url){
      var hyperlink = url;
      if (!hyperlink.match('^https?:\/\/')) {
        hyperlink = 'http://' + hyperlink;
      }
      return space + '' + url + '';
    }
  );
  
};
Categories
Code

RegEx to Extract Video ID from YouTube URLs

The regular expression will extract the video ID from any YouTube URL and it works with shortened URLs (youtu.be) and embed URLs (youtube.com/embed/) as well.


function extractVideoID(url){
    var regExp = /^.*((youtu.be\/)|(v\/)|(\/u\/\w\/)|(embed\/)|(watch\?))\??v?=?([^#\&\?]*).*/;
    var match = url.match(regExp);
    if ( match && match[7].length == 11 ){
        return match[7];
    }else{
        alert("Could not extract video ID.");
    }
}

Another alternative that will extract the video ID as well as the playlist ID from YouTube URLS:

    var id = url.match("v=([a-zA-Z0-9\_\-]+)&?")[1];
    var list = url.match("list=([a-zA-Z0-9\-\_]+)&?");
    list = list ? list[1] : "";