自定义函数的jQuery Uncaught TypeError

Question

In my code I am getting Uncaught TypeError: Cannot read property '1' of null in console but my function looks fine I don't know why its causing this error every time how ever other functions like this I prepared works totally fine Here is working jsFiddle

Here is the part of my code

$(document).ready(function() {
    var URLCheck = document.referrer;
    var frameLocation = URLCheck.match(/:\/\/(.[^/]+)/)[1];
    var whiteLocation = 'mywebsite.com';
    if (whiteLocation == frameLocation) {
        $('#adprimary').remove();
    }
});

Answer 1

Because String.prototype.match returns null if no match was found and you're trying to access the attribute 1 of null .

Check if it's null before accessing any attributes:

var frameLocation = URLCheck.match(/:\/\/(.[^/]+)/);
if(frameLocation !== null) {
  frameLocation = frameLocation[1];
}

Or the short version:

var frameLocation = (URLCheck.match(/:\/\/(.[^/]+)/) || [])[1];

Inside your code:

$(document).ready(function() {
    var URLCheck = document.referrer || ''; // make sure referrer is a string
    var frameLocation = URLCheck.match(/:\/\/(.[^/]+)/)[1];
    if(frameLocation !== null) {
      frameLocation = frameLocation[1];
    }
    var whiteLocation = 'mywebsite.com';
    if (whiteLocation == frameLocation) {
        $('#adprimary').remove();
    }
});

Answer 2

1. the document.referrer may not exists;
2. the URLCheck.match(/:\\/\\/(.[^/]+)/) may be undefined