Ajax, or Asynchronous JavaScript and XML, is a popular web development technique that enables developers to create web applications that can send and receive data without needing the user’s browser to refresh the page. Ajax allows for a better user experience by providing dynamic content - such as images, videos, or text - without having to wait for an entire page to refresh.
Ajax works by making a single request to the server and then receiving data in response. This single request is known as an Ajax call, and it can be used to send data such as user inputs, preferences, or selections directly back to the server. The server will then process this information, generate a response and return the requested data back to the user’s browser. The advantage of this is that it eliminates the need for multiple requests, eliminating wait time and resulting in a better user experience.
Ajax also works using closures - which are functions that remember and have access to variables from their surrounding environment. This allows Ajax calls to remain asynchronous, meaning the client’s browser won’t hang while waiting for the server to respond.
In some cases, a single Ajax call may not be enough to complete a task, so multiple requests can be sent at once. For example, if an application needs to send user preferences to both your database and a third-party API, it may need to make two separate Ajax calls. This can be done using the Promiseobject in JavaScript - which allows us to send multiple requests at once and then wait for all of them to finish before taking further action.
There is also the issue of cross-origin requests when making an Ajax call. This happens when a website requests data from a different domain than the one it was originally hosted on. In this case, web browsers will block the request unless you explicitly allow for cross-origin requests in your code.
Ajax is an incredibly powerful tool for creating dynamic and responsive web applications. By making a single Ajax call or multiple promises each time data is sent to or from the server, developers can ensure that users always receive data without having to wait for a page refresh. This can drastically reduce load times and improve the user experience of an application.