To declare a constant array in JavaScript, you can use the const keyword followed by square brackets, like const arr = [];. The const keyword ensures that the variable arr cannot be reassigned, making it a constant array.

If an element with the correct class name isn't being selected with document.querySelector('.example'), a possible reason could be that the element is not present in the DOM at the time of the query. Ensure that the element you are trying to select exists and is rendered when your JavaScript runs. The other options are less likely causes.

The pop() method in JavaScript is used to remove the last element from an array and return that element. This is commonly used for tasks like removing the last item from a stack implemented as an array. shift() removes the first element, unshift() adds elements to the beginning, and splice() is used for more complex array manipulation.

To handle both resolve and reject outcomes in a single method, you can use the .finally() method after a try block in asynchronous functions. This ensures that the provided code block is executed regardless of whether the Promise is resolved or rejected.

Recursive function expressions, if not designed carefully, can cause infinite recursion, which leads to a stack overflow error. Each recursive call adds a new function call to the stack, and if there's no base case to stop the recursion, it will continue indefinitely. It's essential to have a termination condition to prevent such issues.

The "this" keyword in JavaScript does not refer to the object that calls the function in the global context. In the global context, "this" points to the global object, which is usually the "window" object in browsers. This can be a source of confusion, so it's essential to understand the various contexts in which "this" behaves differently.

A closure in JavaScript is a function that "remembers" its lexical scope, even when it's executed outside that scope. This allows the function to maintain access to variables from its parent scope, creating a powerful mechanism for encapsulation and data privacy.

The unshift() method is used to add elements to the beginning of an array. It's particularly useful when you want to insert one or more elements at the start of an existing array without affecting the order of the existing elements. Unlike push(), which adds elements to the end, unshift() works at the beginning.

In Node.js, when you define a regular function in the global scope (outside any function or module), "this" inside that function refers to the Node.js global object (e.g., "global" in Node.js or "window" in the browser). This behavior is different from client-side JavaScript, where "this" in the global scope refers to the global window object.

In JavaScript, the setTimeout function is often used for delaying the execution of a function in an asynchronous manner. It schedules the execution of a function after a specified time delay, allowing for tasks like animations or asynchronous operations to be handled.