How to Fix and Handle Undefined Variables in JavaScript Like a Pro?

I totally get how frustrating undefined variable errors can be, especially when you’re not sure if it’s a scope problem or just a missing declaration. When working on projects like your client’s Spirituality Animals, I always start by making sure every variable is properly declared using let, const, or var. Then, I use tools like ESLint to catch undeclared or unused variables early. For tricky cases, I check variable scope carefully and use typeof to safely test if a variable is undefined before using it. Also, applying default values with the nullish coalescing operator (??) helps avoid unexpected errors. These practices have really helped me spot and fix issues quickly, keeping my code clean and reliable.