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JavaScript JavaScript Basics Making Decisions in Your Code with Conditional Statements The Conditional Challenge Solution

How to fix 'null' issue if a user selects: 'Cancel' on prompt?

Not really part of the challenge but I'm just curious...

My program runs fine, but if a user were to select 'Cancel' on one of my prompts, the program encounters an error:

Uncaught TypeError: Cannot read property 'toUpperCase' of null

What is a solution to this?

1 Answer

Steven Parker
Steven Parker
211,091 Points

One approach would be to confirm that the response is not null first, to treat null as a wrong answer:

if (answer1 != null && answer1.toUpperCase() == "RUBY") {
  correct += 1;
}

Other strategies would include a separate test for null, and either ending the program or asking the question again.