The HTTP status code '200' indicates a successful GET request. It means that the request was received, understood, and the server has responded with the requested data. Other status codes like 300 (redirect), 400 (client error), and 500 (server error) signify different types of issues or responses. Understanding status codes is crucial for handling HTTP requests properly in JavaScript.

To add a new item to the beginning of an array in JavaScript, you can use the arr.unshift(newItem); method. This will insert newItem at the start of the array, shifting the existing elements to the right. push() adds to the end of the array, append() and insert() are not standard array methods.

The for...of loop is used to iterate over the values of an array, making it useful for accessing the elements directly. Unlike the for...in loop, which iterates over properties, for...of provides a simple way to loop through the contents of an array.

If your code to select an element by its ID isn't working, one possible reason could be a typo in the ID selector. IDs are case-sensitive, so make sure it matches the ID attribute in the HTML exactly. The other options are less likely causes: missing libraries would generally cause JavaScript errors, and CSS hiding doesn't affect element selection.

The for...of loop in JavaScript is used for iterating over iterable objects like arrays, strings, maps, and sets. By default, it iterates over the values of an iterable, making it a convenient choice for iterating through the elements of an array or the characters of a string, for example. It doesn't work with plain objects (non-iterable) and would require additional steps or methods to iterate over object properties.

The event.target property in JavaScript gives access to the element that triggered the event. It's especially useful in event delegation and can be used to identify which specific element was interacted with in a group of similar elements.

When a function declaration and a var variable with the same name are hoisted in the same scope, the function declaration takes precedence and shadows the var variable. This is known as "hoisting," and it means that the function is accessible throughout the scope, even before its actual declaration in the code.

In React, when using the function keyword to define a custom method within a component class, you need to manually bind the function to the component instance in the constructor using "this.functionName = this.functionName.bind(this);" to ensure that "this" refers to the component instance and not the function itself.

Unlike function expressions, function declarations are hoisted. This means they are moved to the top of their containing scope during compilation, allowing you to call them before they are defined in the code. Function expressions are not hoisted in the same way.

JavaScript was initially designed to make web pages more interactive. It allowed developers to create dynamic and engaging web content by manipulating elements on web pages in response to user actions. This interactivity revolutionized web development.