Why regex is giving me Uncaught TypeError: Cannot read properties of null (reading '1')?

I have this form

<form onsubmit="return false">
  <p>Enter the URL:</p><input id="ur" type="text" name="url">
  <button type="submit" class="button secondary" id="myBtn" onclick="myFunction();" value="Load">Load</button>
</form>

<p id="demo"></p>

I have this function

function myFunction(){   
  var inputString = document.getElementById("ur").value;
  var result = inputString.match(/http:\/\/(?:.*\.|.*)imdb.com\/(?:t|T)itle(?:\?|\/)(..\d+)/i);
  document.getElementById("demo").innerHTML = result[1];
}

Result is

Uncaught TypeError: Cannot read properties of null (reading '1')

I am not sure where I am making mistake in my function.

I am expecting to get

tt8760708

from

https://www.imdb.com/title/tt8760708

on click on button as you can see.

>Solution :

Change your function to this:

function myFunction(){   
  var inputString = document.getElementById("ur").value;
  var result = inputString.match(/^(?:https?:\/\/)?(?:www\.|m\.)?(?:imdb.com\/title\/)?(tt[0-9]+)/i);
  document.getElementById("demo").innerHTML = result? result[1]: '';
}