In JS, Array ([1, 2, 3] syntax) is both a stack and queue (and an array). Object ({a: 1} syntax) is Hashmap-like (and Map is an actual Hashmap). You may learn to use them in the context of applying these data structures to real life scenarios in a bootcamp or tutorial, but they are not going to teach you the theory of what makes a stack different than a queue, or why any of that might matter. You're rarely ever going to be resource constrained in JS, so for early webdev career, it may not matter beyond mentioning names of data structures in interviews and knowing how to use the built-in types. For stuff beyond frontend, the nomenclature for Array/Object equivalents will look more like algo classes (HashMap, ArrayList, etc) and you may actually need to worry about the characteristics of various data structures, especially once you get into crunching a lot of data. More on reddit.com

While in actual work you'll rarely implement these yourself, it's still a good idea to know how they work as they are fundamental data structures. Also they commonly come up in interview questions. More on reddit.com

I can't quite tell what it is you're claiming about circular queues. If you used five or six full sentences instead of one long one here, I think that would help. So, to try to answer your question generally: Circular queues are less amenable to expansion than simple queues. So they're a good fit where you only need a fixed amount of storage, and you don't want the runtime overhead of allocating memory for new queue members. (And if the size is fixed, you will tend to allocate more memory than you need, to ensure you always have enough.) I've used circular queues in low-level networking code, where speed was important, and I was reading off a fixed-sized buffer anyway. Circular queues attain these special characteristics by being more complex than simple queues under the hood. That is a basic tradeoff of all the more-sophisticated data structures, with potential pitfalls including lower understandability and maintainability, and higher chance of errors. And there are more-neutral tradeoffs, like the speed vs. memory tradeoff I just mentioned. More on reddit.com

If you need a data structure that provides O(1) access of the first element inserted then use a queue. If you need O(1) access of the last element then use a stack. A queue is often associated with a breadth first search while a stack is often utilized for depth first search. Edit - a priority queue is an abstract base class that typically is built with a heap. So if I was deciding between a priority queue/stack/queue then I’d question how many times I’d be accessing my top element. When you pop from the top of a priority queue it takes some sorting of at least O(logk) to maintain the heap invariant. Whereas popping from a stack/queue is O(1) as no reordering is necessary if you pop from the proper end. Long story short - for a beginner then you’d probably wanna go with queues/stacks before heaps IMO. More on reddit.com