Question

Write a JS function that extracts links from a given text. The text will come in the form of strings, each representing a sentence. You need to extract only the valid links from it.

Example:

“www.internet.com”

• Sub-Domain: www
• Domain name: internet
• Domain extension: com

---

• The Sub-Domain must always be “www”.
• The Domain name can consist of English alphabet letters (uppercase and lowercase), digits and dashes (“–“).
• The Domain extension consists of one or more domain blocks, a domain block consists of a dot followed by one or more lowercase English alphabet letters, a Domain extension must have at least one domain block in order to be valid.

The Sub-Domain and Domain name must be separated by a single dot. Any link that does NOT follow the specified above rules should be treated as invalid.

Example incorrect links:  

• "ww.justASite.bg"
• "lel.awesome.com"
• "www.stamat_gosho.hit.bg"
• "www.no-symb#^ols-allow%ed.com"
• "www.pesho.12"
• "www.gosho-site."
• "www.example-site._*^#"

Example correct links:  

• "Some textwww.softawerun.bg"
• "Just a link in a www.sea-of-text.bg-swimming around"
• "Instruments www.Instruments.rom.com.trombone2000 Instrument here"
• "All your ice cream flavors-www.scream.for.ice.cream(We  also have squirrels)"

The input comes as array of strings. Each element represents a sentence.

Examples for the task:

Input:
Join WebStars now for free, at www.web-stars.com
You can also support our partners:
Internet - www.internet.com
WebSpiders - www.webspiders101.com
Sentinel - www.sentinel.-ko

Output:
www.web-stars.com
www.internet.com
www.webspiders101.com

---

Input:
Need information about cheap hotels in London?
You can check us at www.london-hotels.co.uk!
We provide the best services in London.
Here are some reviews in some blogs:
"London Hotels are awesome!" - www.indigo.bloggers.com
"I am very satisfied with their services" - ww.ivan.bg
"Best Hotel Services!" - www.rebel21.sedecrem.moc

Output:
www.london-hotels.co.uk
www.indigo.bloggers.com
www.rebel21.sedecrem.moc

---

The output is all valid links you’ve found, printed – each on a new line.

Answer 1

Interesting task soled with regex:

function extractLinks(arrStr) {
    let pattern = /(www)\.([a-zA-Z0-9-]+)(\.[a-z]+){1,}/g;

    let result = "";
    for (let arrS of arrStr) {
        let matches = arrS.match(pattern);
        if (matches != null) {
            result += matches + "\n";
        }
    }
    console.log(result);
}

extractLinks([
    "Join WebStars now for free, at www.web-stars.com",
    "You can also support our partners:",
    "Internet - www.internet.com",
    "WebSpiders - www.webspiders101.com",
    "Sentinel - www.sentinel.-ko"
]);