UX Engineers at Aptible play an important role in the product development process by blending UX knowledge with technical skills to fill the gap between design and engineering.

Existential checks are when we have to detect whether or not a variable has a value - that is, checking to see if a variable exists. If the value is null, undefined or otherwise falsy, then it fails the check. This usually takes the form of an if-statement.

Let’s say you’ve created a SaaS application that lets customers keep track of their vendors. Things are going well and you’re adding many customers. One day, a curious customer starts messing around with the IDs in URLs and stumbles across a vendor they shouldn’t have access to. This is Very Bad™, especially if your customers are relying on your application to store sensitive information!