AJAX is a very important part of web development practices. We usually do AJAX request to load data seamlessly to improve User Experience.
AJAX is a way to communicate with server without waiting for the response. When AJAX completes or fails it returns some response and based on those responses we take decisions, render data etc.
When you are going for an interview for the position of Back End Developer , Front End Developer or even Full Stack Developer, you must have an overview of how AJAX works. This is a part of JavaScript Interview.
Here we have listed few questions and will be improving answers and will be adding more questions to this section. All the best .
What is AJAX?
AJAX stands for Asynchronous JavaScript and XML. It is a web development technique used for creating interactive web applications. AJAX allows for the creation of dynamic, responsive web applications that can be fast and user-friendly.
AJAX facilitate a web pages to be updated asynchronously by exchanging data with a web server in background. It can update the web-page without reloading the whole page.
How does AJAX work?
AJAX works by exchanging small amounts of data with the server behind the scenes. This exchange of data is done asynchronously, meaning that the web page can continue to be used while the data is being retrieved. When the data is received, it can be used to update the web page without having to reload the entire page.
What are the main components that are used by AJAX?
AJAX components are :
- A browser built-in XMLHttpRequest object
- JavaScript and HTML DOM
What is XMLHttpRequest Object?
The XMLHttpRequest object can be used to request data from a web server without refreshing the whole page.It can send data to server in background and can request and receive data in background.
What are the request type used by XMLHttpRequest Object?
open() : It specify the type of request GET or POST
send() : Sends the GET request to the server
send(string) : Sends the POST request to the server
Give an Example of jQuery AJAX call.
A POST method AJAX example in jQuery:
var empId = $("ul .emp").first().attr("id");
var request = $.ajax({
url: "myajaxcall.php",
type: "POST",
data: {id: empId},
dataType: "json"
});
request.done(function (response) {
console.log(response);
});
request.fail(function (jqXHR, ajax_status) {
alert("Request failed: " + ajax_status);
});
What is difference between xhr.status and xhr.readyState.
xhr.status : used to determine whether the request was successful or not.
xhr.readyState : the state of the request’
xhr.readyState zero(0) means “has not yet been sent”
xhr.readyState zero(4) means “complete and response received”
The server provides the status, while the user agent provides the readyState.
What are the benefits of using AJAX?
Some of the benefits of using AJAX include:
- Faster web page loading times
- Reduced server load
- Increased interactivity and responsiveness
- Better user experience
What are the disadvantages of Ajax?
Yes , AJAX looks good, but it could be a threat to your system.
Why this is so? When a AJAX happen the data can be easily in browsers and one can easily make some API call using those parameters.
False data can easily injected to this request and it may harm our server our database.
AJAX does not wait for response to render things, so sometimes it is very tricky to use AJAX and wait for Data to render and then perform actions on those data.
Here are few tips to avoid any harmful Injection:
- Use data encryption in request .
- Sanitise the data received in AJAX request before doing any operation on it.
- Use CSRF Token.
- Don’t expose your parameters directly
Can we use the HTTP methods in AJAX call?
Yes , We can use GET, POST, PUT, DELETE etc methods in AJAX call.
What are some of the drawbacks of using AJAX?
Some of the potential drawbacks of using AJAX include:
– Increased complexity of the web page code
– Increased reliance on JavaScript
– Potential browser compatibility issues
What is an AJAX request?
An AJAX request is an HTTP request that is made using JavaScript. AJAX requests are used to exchange data with a web server asynchronously.
What is an AJAX response?
An AJAX response is the data that is returned from an AJAX request. AJAX responses can be in the form of HTML, XML, or JSON.
What is an AJAX callback?
An AJAX callback is a function that is executed after an AJAX request is completed. Callbacks are used to handle the response data and update the web page accordingly.
What is an AJAX callback?
An AJAX callback is a function that is executed after an AJAX request is completed. Callbacks are used to handle the response data and update the web page accordingly.
What is an AJAX action?
An AJAX action is a JavaScript function that is triggered by an AJAX request. AJAX actions are used to handle the request and response data.
What is an AJAX method?
An AJAX method is a JavaScript function that is used to make an AJAX request. The most commonly used AJAX method is the XMLHttpRequest object.
What is an AJAX library?
An AJAX library is a set of JavaScript functions that are used to make AJAX requests. The most popular AJAX library is jQuery.
What is jQuery?
jQuery is a JavaScript library that makes it easy to make AJAX requests. jQuery also provides a number of other features that are helpful for web development.
What is the jQuery.ajax() method?
The jQuery.ajax() method is a method of the jQuery library that allows for the creation of AJAX requests.
What are the parameters of the jQuery.ajax() method?
The jQuery.ajax() method takes a number of parameters. Some of the most commonly used parameters are:
– url: the URL of the server that will handle the request
– type: the type of request (GET or POST)
– data: the data that will be sent to the server
– success: a callback function that will be executed if the request is successful
– error: a callback function that will be executed if the request is unsuccessful
What is an AJAX example?
A simple AJAX example would be a web page that allows for the submission of a form without reloading the entire page. When the form is submitted, an AJAX request is made to the server. The server processes the form and returns a response. The web page is then updated with the response data without having to reload the entire page.
What is an AJAX application?
An AJAX application is a web application that uses AJAX technology. AJAX applications are typically more responsive and user-friendly than traditional web applications.
What is the difference between an AJAX request and an AJAX response?
An AJAX request is an HTTP request that is made using JavaScript. An AJAX response is the data that is returned from an AJAX request.
What is the difference between an AJAX callback and an AJAX action?
An AJAX callback is a function that is executed after an AJAX request is completed. An AJAX action is a JavaScript function that is triggered by an AJAX request.
What is the difference between an AJAX method and an AJAX library?
An AJAX method is a JavaScript function that is used to make an AJAX request. An AJAX library is a set of JavaScript functions that are used to make AJAX requests.
What is the jQuery.ajax() method?
The jQuery.ajax() method is a method of the jQuery library that allows for the creation of AJAX requests.
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