JavaScript runtime error: Unable to get property 'split' of undefined or null reference

Question

While debugging I got this error in my below part of code..

 queryStirngValue = document.referrer.split("myQuryString")[1].split("%")[1].split("253D")[1];
    alert(queryStirngValue);

Answer 1

 document.referrer.split("myQuryString")[1].split("%")

You first split on myQuryString (which by itself is misspelled?)

With [1] you then want the second array value (because arrays start at 0)

So if myQuryString is not in the QueryString you now have a null value

So

null.split("%")

causes: Uncaught TypeError: Cannot read property 'split' of undefined(…)