Closures in JavaScript are powerful because they allow functions to remember and access their outer (enclosing) variables even after the outer function has finished executing. This feature can lead to memory usage if not managed properly, but it's not a limitation or disadvantage of closures per se.

The else if statement is used to specify a new condition to test if the first condition in an if statement is false. It allows for branching in code execution based on multiple conditions. It's a fundamental control structure in JavaScript.

JavaScript's sort() method by default converts elements to strings and then compares their UTF-16 code units. This means that if the array contains mixed data types, the sorting order might be unexpected. For proper sorting, you should provide a compare function as an argument to sort().

When a piece of code returns -Infinity, it is usually due to a division operation where you are dividing a finite number by zero. In JavaScript, dividing any finite number by zero results in -Infinity. Make sure to handle cases where division by zero can occur to prevent unexpected -Infinity values in your code.

In JavaScript, the typeof operator is used to determine the data type of a variable. When var x = "5"; is encountered, the value of x is a string because it is enclosed in double quotes. Therefore, typeof x will return "string". It's important to note that JavaScript is dynamically typed, meaning the type of a variable can change during runtime.

You can add a method to an object in JavaScript by defining a function and assigning it as a property of the object. For example, myObject.myMethod = function() { /* method code */ };. While you can use various patterns and techniques for method definition, there's no standard Object.addMethod() or Object.method() function.

In JavaScript, hoisting is the mechanism by which variable and function declarations are moved to the top of their containing scope during compilation. This means that you can call a function declared with function before it appears in your code, and it will still work. However, it's important to note that only the declarations are hoisted, not the initializations. Understanding hoisting is crucial for writing clean and maintainable JavaScript code.

In AJAX (Asynchronous JavaScript and XML), the XMLHttpRequest object is used to perform HTTP requests asynchronously. It allows you to send and receive data from a server without refreshing the entire web page.

To prevent the default action of an event in JavaScript, you commonly use the event.preventDefault() method. It stops the default behavior associated with the event, such as preventing a form from submitting or a link from navigating to a new page. This method is crucial for controlling the behavior of events.

The for...of loop is most suitable for iterating over object properties when you want to create an array of strings. It directly iterates over iterable values like arrays and works well for this task by extracting key-value pairs from the object.