The comparison operator == (Equality) performs type coercion if the operands are of different types. This means JavaScript will attempt to convert the operands to the same type before making the comparison. In contrast, === (Strict Equality) checks both value and type without coercion.

JavaScript was introduced to the world in 1995. It was first released as part of Netscape Navigator 2.0. This event marked the beginning of JavaScript's journey as a popular and widely used scripting language for web development.

JavaScript performs type coercion when comparing values. In this case, the empty array [] is truthy, and ![] evaluates to false. When comparing, the empty array is coerced to false, resulting in true. This behavior can be surprising and is a common gotcha in JavaScript.

XMLHttpRequest is a crucial object used in AJAX (Asynchronous JavaScript and XML) to make HTTP requests to the server and interact with server-side data without requiring a page reload. It allows for asynchronous communication with the server, making web applications more dynamic and responsive.

When the pop() method is applied to an empty array in JavaScript, it returns undefined and does nothing to the array. There are no elements to remove, so it simply returns undefined without causing any errors.

A function expression is preferred over a function declaration when you need to define a function inside an object, pass it as a callback function, or use it in a specific local scope. Function expressions are often used in scenarios where you want to create functions on the fly and keep them within a limited scope.

The 'break' statement exits a while loop immediately and continues executing the code that follows the loop at the next line. It allows you to prematurely terminate a loop based on a certain condition, without completing the remaining iterations.

This is possible due to "Variable Hoisting" in JavaScript. Variables declared with var are hoisted to the top of their containing function or global scope. This means that the variable is accessible anywhere within that scope, even before its actual declaration in the code.

To abort a fetch request when the user navigates away from the current page, you should implement an if statement that checks the navigation state and cancels the request accordingly. The other options are not suitable for this specific task, and there's no built-in fetch.abort() method in JavaScript.

An arrow function is defined using the => (fat arrow) symbol. This concise syntax is a shorthand for writing simple, one-liner functions in JavaScript. It's especially useful for functions that have no side effects and return a single expression. The => symbol distinguishes arrow functions from traditional function declarations.

In JavaScript, a Promise can be in one of three states: Pending (initial state), Resolved (fulfilled with a value), or Rejected (fulfilled with an error). "Completed" is not a valid state for a Promise; it's either resolved or rejected.

The myArray.find(callback) method returns undefined if no element in the array passes the test provided by the callback function. This is because it signifies that no element satisfies the condition. If an element is found that passes the test, it returns that element.