The keyword used to stop a loop prematurely in JavaScript is "break." When "break" is encountered within a loop, it immediately exits the loop, even if the loop condition is still true or there are more iterations remaining. This is useful for early termination of a loop based on a specific condition. "continue" skips the current iteration and moves to the next one, while "exit" and "return" have different purposes and are not used for loop control.

In a while loop, if you forget to update the condition, it can lead to an "infinite" loop, where the loop continues to execute indefinitely. This can cause the program to hang or become unresponsive. It's important to ensure that the loop's condition is updated to eventually become false.

The splice() method should be avoided when removing elements from an array in a performance-critical application because it has a time complexity of O(n) due to the need to shift elements after the removal. Methods like pop() (O(1)), shift() (O(1)), or slice() (O(n)) may be more appropriate.

To troubleshoot the issue of a variable not retaining an expected value within a nested function, you should explore the concept of lexical scoping. Lexical scoping (also known as static scoping) means that the scope of a variable is determined by its location within the source code, and nested functions have access to variables from their containing (parent) functions. This understanding will help you identify and fix the problem.

To handle multiple data types efficiently in a switch statement, you can create an array of functions, where each function corresponds to a specific data type. When you receive input, you can then call the appropriate function based on the data type, which offers more flexibility and avoids type conversion complexities.

The statusText property of the Response object represents the status text of the HTTP response. It provides a textual description of the HTTP status code, such as "OK" for status code 200 or "Not Found" for status code 404. This property is useful for understanding the meaning of the response status code in a more human-readable form.

When dealing with callbacks, the first argument is traditionally reserved for Error. This convention allows developers to handle errors gracefully when executing asynchronous operations. It helps in proper error handling and prevents unexpected crashes in your code.

The status property in an HTTP response is used to indicate the HTTP status code for the response. HTTP status codes provide information about the outcome of an HTTP request, such as whether it was successful (e.g., status code 200 for OK) or encountered an error (e.g., status code 404 for Not Found). It helps the client understand the result of the request.

This pattern is known as a "Higher-order Function." In JavaScript, higher-order functions are functions that can take other functions as arguments or return them. This enables functions to maintain access to their lexical scope, creating closures.

You can create a new HTML element in JavaScript using the createElement() method. This method is used to dynamically generate HTML elements in your code. It takes the name of the HTML tag you want to create as an argument.

The arithmetic operator '++' is known as the increment operator. It increases the value of a variable by 1. For example, if you have a variable x and you write x++, it will increment the value of x by 1. This is commonly used in loops and counters in JavaScript.

When optimizing code that returns a function and accesses variables outside of its own scope, you should consider the concept of function closures. Function closures allow an inner function to "remember" and access variables from its containing (parent) function's scope even after the parent function has finished executing. This can be useful for encapsulating state and optimizing code.