Hello!
I’ve edited your code to improve readability. In the future, please be sure to format your code as explained here 
.
In regards to your code, that’s not the right JavaScript syntax.
if (isPangram = 'a'...'z') is assigning a value to isPangram instead of comparing. On the other hand, that’s not the correct way to define an array (assuming that’s what you want).
To declare and initialize an array, you write this: let myArray = ['a', 'b', 'etc.'];.
Please, make sure you have the right syntax first, otherwise it will never work .
I recommend you take the FreeCodeCamp course on JavaScript.