Check if URL is Valid with canParse()

Here's an interesting method I just discovered.

On the URL object, we can access a method called canParse() (URL.canParse()) that lets us check that a given URL is valid.

How to

To use it, simply pass a URL to the URL.canParse() method and it will return true if valid, otherwise it will return false.

The syntax is pretty simple:

URL.canParse(url, optionalBaseValue)

The url, parameter being the URL and optionalBaseValue is an optional value that defaults to undefined.

I think some examples will help it make sense:

// Test valid URL
 URL.canParse(""): true

// Test relative URL (no base)
 URL.canParse("/articles"): false

// Test relative URL with valid base URL
 URL.canParse("/articles",""): true

// Not a URL 
URL.canParse("penis"): false

This can be handy in certain use cases such as constructing a URL with new URL(""). Because if you pass new URL a invalid value it will throw a TypeError meaning usually I would wrap it in a try/catch block.

Here's a little example:

function createURLSafely(urlString) {
  // Use URL.canParse() to check if the urlString is a valid URL
  if (URL.canParse(urlString)) {
    // If the URL is valid, construct the URL object
    return new URL(urlString);
  } else {
    // If the URL is not valid, handle the case accordingly (e.g., return null or log an error)
    console.error("Invalid URL:", urlString);
    return null;

// Example usage:
const safeURL = createURLSafely("");
if (safeURL) {
  console.log("URL created successfully:", safeURL);
} else {
  console.log("Failed to create URL.");

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Avatar for Niall Maher

Written by Niall Maher

Founder of Codú - The web developer community! I've worked in nearly every corner of technology businesses; Lead Developer, Software Architect, Product Manager, CTO and now happily a Founder.


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