URL.canParse

Parsing of URLs on the shopper facet has been a typical observe for twenty years. The early days included utilizing illegible common expressions however the JavaScript specification finally advanced right into a new URL technique of parsing URLs. Whereas URL is extremely helpful when a legitimate URL is supplied, an invalid string will throw an error — yikes! A brand new technique, URL.canParse, will quickly be accessible to validate URLs!

Offering a malformed URL to new URL will throw an error, so each use of new URL would should be inside a attempt/catch block:

// The right, most secure manner
attempt {
  const url = new URL('https://davidwalsh.title/pornhub-interview');
} catch (e) {
  console.log("Dangerous URL supplied!");
}

// Oops, these are problematic (principally relative URLs)
new URL('/');
new URL('../');
new URL('/pornhub-interview');
new URL('?q=search+time period');
new URL('davidwalsh.title');

// Additionally works
new URL('javascript:;');

As you possibly can see, strings that might work correctly with an <a> tag generally will not with new URL. With URL.canParse, you possibly can keep away from the attempt/catch mess to find out URL validity:

// Detect problematic URLs
URL.canParse('/'); // false
URL.canParse('/pornhub-interview'); // false
URL.canParse('davidwalsh.title'); //false

// Correct utilization
if (URL.canParse('https://davidwalsh.title/pornhub-interview')) {
  const parsed = new URL('https://davidwalsh.title/pornhub-interview');
}

We have come a good distance from cryptic regexes and burner <a> parts to this URL and URL.canParse APIs. URLs signify a lot greater than location today, so having a dependable API has helped net builders a lot!