How to count all domains from http:// adresses list by regular expressions?

Question

So, I have a list of http:// adresesses and I need to count domains by regular expressions in JS. I don't have idea how to do that, as they have different length and some are similar to each other. How can I achieve that? Regular expressions are my nightmare. here is my list

Answer 1

Using modified regular expression from this thread What is a good regular expression to match a URL? you can count the number of matches like this:

// Your original list of addresses
const data = `
http://www.gaba.ch/fr_CH/519/Netuschil-L-et-al-Eur-J-Oral-Sci-103-1995-355-361.htm?Subnav2=ResearchProducts&Article=17516
http://www.gaba.fi/fi_FI/725/Suche.htm?Page=42
http://www.gaba.ch/fr_CH/538/Recomend-Page.htm?LinkID=576&Brand=meridolHalitosis&Subnav=&Product=312435
http://www.gaba.com/en/1071/Professor-Edwin-G-Winkel.htm
http://www.gaba.ch/fr_CH/580/Congress-Calendar.htm?CongressId=289461&Page=6
// ... etc
`;

// Make sure you include the g flag to find all the matches and not just one
const addresses = data.match(/https?:\/\/(?:www\.)?[-a-zA-Z0-9@:%._\+~#=]{2,256}\.[a-z]{2,6}\b(?:[-a-zA-Z0-9@:%_\+.~#?&//=]*)/g);

// Get length of the matched array
// - In this example: 5
// - In your case: 4815
const addressesCount = addresses.length;

EDIT:

Based on your comment I made few adjustments to the code:

// Your original list of addresses
const data = `
http://www.gaba.ch/fr_CH/519/Netuschil-L-et-al-Eur-J-Oral-Sci-103-1995-355-361.htm?Subnav2=ResearchProducts&Article=17516
http://www.gaba.fi/fi_FI/725/Suche.htm?Page=42
http://www.gaba.ch/fr_CH/538/Recomend-Page.htm?LinkID=576&Brand=meridolHalitosis&Subnav=&Product=312435
http://www.gaba.com/en/1071/Professor-Edwin-G-Winkel.htm
http://www.gaba.ch/fr_CH/580/Congress-Calendar.htm?CongressId=289461&Page=6
// ... etc
`;

// Find all valid domains (excluding http and www)
const addresses = data.match(/https?:\/\/(?:www)?\.((?:.+?)\.[\w\.]{2,5})/g);

// Filter the addresses to only unique ones
const unique = addresses.reduce((acc, cur) => acc.indexOf(cur) > -1 ? acc : acc.concat(cur), []);

// Get number of unique addresses found
// - In this example: 3
// - In your case: 28
const length = unique.length;

Note: addresses like this http:/www.bnf.org/bnf/bnf/54/%3C won't be matched because they are not valid.

Answer 2

You can use String.prototype.match() method.