Uncaught TypeError: URL is not a constructor in javascript

Question

my code

let url = new URL('http://www.test.com/t.html?a=1&b=3&c=m2-m3-m4-m5');
let searchParams = new URLSearchParams(url.search);
console.log(searchParams.get('c'));  // outputs "m2-m3-m4-m5"

and the error

Uncaught TypeError: URL is not a constructor

Answer 1

The only thing that would cause this error in any recent version of Chrome (at least since 2014's v32) would be if you had some other code that overwrote the URL symbol.

For example

const URL = 'I am now a string'

// later...

let url = new URL('http://www.test.com/t.html?a=1&b=3&c=m2-m3-m4-m5');

If you're having trouble locating the code that's overwriting URL, you could start by simply adding

console.log(URL)

to your code. The value logged may give you a hint. Otherwise, see this post ~ How to know in which file that defined a js global var in chrome console?

---

Solutions:

• Try not to use global object names in your variables.
• Don't assign global variables if you can help it.

On that last note, you could avoid this problem like this

(function() {
  const URL = 'I am a string but not window.URL'

  // later...

  let url = new window.URL('http://www.test.com/t.html?a=1&b=3&c=m2-m3-m4-m5');
  console.info(url.search)
})()