The method getElementById selects an element by its ID attribute. It returns the element with the specified ID attribute, providing a direct and efficient way to access an element in the DOM by its unique identifier.

A recursive function expression can be named, allowing it to refer to itself by name. This is useful in cases where a function needs to call itself during its execution, typically seen in solving recursive problems or implementing recursive algorithms.

Polymorphism allows different car types (e.g., sedan, truck) to have their own implementations of the fuel efficiency calculation method while inheriting common attributes and behaviors from the general Car class. This ensures flexibility and extensibility in your game.

To adhere to the Liskov Substitution Principle, you should add the method specific to "Admin" in the "Admin" class. This ensures that each derived class (Admin and Guest) can be used interchangeably with the base class (User) without violating the principle.

The keyword used to check a condition in JavaScript is if. It allows you to execute a block of code if a specified condition evaluates to true. The if statement is fundamental for controlling the flow of your JavaScript program.

JavaScript supports lexical scoping by allowing functions to access variables defined in their containing (enclosing) functions. This means that inner functions can "see" and use variables from outer functions, creating a chain of scope. This is achieved by nesting functions. Modern JavaScript also introduced 'let' for block-level scoping.

Arrow functions are not recommended for use as event handlers in the DOM. This is because the value of "this" in an arrow function is not determined by the event but instead retains the value from its enclosing lexical context, which may not be what you expect in an event handler. Traditional functions are usually preferred for event handlers.

The default case in a switch statement serves as a fallback option. If none of the other cases match the expression's value, the code in the default case block is executed. This ensures that there is always a valid path in the switch.

The for...of loop handles string iteration by iterating over each character in the string. It treats the string as an iterable object where each character is an element, allowing you to loop through and process individual characters in a string efficiently.

JavaScript was first implemented in Netscape Navigator. Brendan Eich developed it in 1995 while working at Netscape Communications. This move by Netscape added a significant interactive element to the web and contributed to the rapid adoption of JavaScript.

JavaScript implements inheritance through a prototype chain and object delegation. Each object has a prototype object, and if a property or method is not found on the object itself, it's looked up on the prototype chain. This mechanism allows objects to inherit properties and methods from their prototypes, facilitating code reuse and object-oriented programming in JavaScript. Classes and interfaces are not directly related to inheritance in JavaScript.

The comparison operator '!==' checks for inequality while also considering type coercion. It returns true if the values are not equal or if their types are not the same. For example, 5 !== "5" would evaluate to true because the number 5 is not equal to the string "5."