When I googled about React.js what I got is: React.js is a Framework that is used to create user interfaces. If a particular part of the website is frequently updated that means we can use react. But I am confused that Ajax has been used for this only. We can update a part of site using Ajax without page refresh. For templating we would be using handlebars and mustache. Could somebody explain me in what ways react is different from Ajax and why we should use it.
In short, React uses AJAX. They are not related in the way you're asking.
Keep reading for a crash course in what React is, what AJAX is, and how they are used to make modern web applications.
This is probably a more simple explanation than you're looking for, but for anyone else who may be confused...
AJAX and Airplanes
Think about an Airplane. The most important part of an airplane is that it flies. But an airplane also has wheels. And the wheels serve a very important purpose, because without them the airplane would never fly or land, and despite all the awesome stuff a plane could do in the air, it wouldn't matter without wheels.
This is the same relationship that React has with AJAX. React is the airplane, and AJAX are the wheels. But, ya know, other things have wheels too. Tractors, cars, even some boats have wheels, and they're all very important, and crippled without wheels. So too is AJAX to other web technologies, but when you're talking about airplanes, its wheels are usually the farthest thing from your mind.
So React is to AJAX, what an Airplane is to Wheels.
But let's talk about AJAX. What is it? Why is it so important? How it is used in websites today. Then I'll show how it's used by React. Then show you what React does that's so impressive, it makes you forget about AJAX - Like an Airplane to its wheels.
Remember Websites in the 90's?
When you clicked anything, a new page would have to load to show the effect of your click - even if it was nothing. Here's an awesome example. Go to that page and click around... See how clicks whisk you away to a completely different page? That is the Internet before AJAX.
Now, take a look at this very page: next to each answer is an Up Arrow... Go ahead and click one of them... Notice the page doesn't reload, but you are given feedback: the arrow turns Orange. This may seem insignificant, but it represents big advancements in web technology: AJAX, or more accurately: the AJAX approach to web development.
The AJAX approach allows that to happen! And this is no big deal now; it's so intrinsic to the web experience, it's difficult to imagine the Internet without it.
AJAX and a Clock Face
A good analogy of the AJAX methodology, and how it changed the web is a simple wrist watch, or a wall clock... Imagine the minute, hour and second hands moving around the clock's face to show time. Now, suppose every movement of the second hand caused the entire clock to be destroyed and rebuilt?
All that effort of destroying and rebuilding just to show a tiny change?! Well, that would be an outrageous waste of resources, and that was the Internet of the 90's. Thankfully, we have AJAX now. Just as a clock seamlessly displays the time, AJAX allows web pages to show changes in data immediately, without the page needing to be refreshed; you click an up arrow, and it turns orange. No page reload needed!
Originally, AJAX was just the name given to using existing technologies together to show simple updates to the user, but it has become so intrinsic to the web experience that unless you know what you're doing, you wouldn't even know you're using it. For instance, fetch is the preferred way to accomplish the AJAX approach since 2015. Before that it was XMLHttpRequest - even though JSON was used to transfer data more often because it's less verbose. JQuery is the only web technology that actually says AJAX ($.ajax()) to my knowledge, but you typically wouldn't (and shouldn't unless you really know what you're doing) use JQuery with a react application.
And AJAX works just like webpages:
The user performs an action (like pressing an up arrow)
A client (A Web Browser like Firefox) requests data from a server (like the Stack Overflow (SO) Server).
The server processes the request (updates the database to record the upvote).
The server sends a response back to the client that says if the action was successful or not.
Finally, some of the code already loaded into the web page, decides how to process this new information (in our example, javascript would add a class to the up-arrow and CSS rules would dictate that elements with that class are orange).
The user only sees that the arrow is orange. All the other steps are hidden so it seems like one seamless, responsive action.
Single-Page Applications
Since we're not rebuilding the entire page with every click, you can keep information about the site stored in the browser. This can be used throughout your entire visit and future visits.
The first time you visit Stack Overflow, all of the CSS, JS, and HTML is loaded. These three languages define the style (CSS), behavior (JS), and structure (HTML) of the data sent back and forth from the server. And guess how that data is sent! AJAX.
This is how most of the web works now. Google, Facebook, Amazon, Youtube, Reddit, every site built with WordPress and WIX, even Stack Overflow - they all use this basic paradigm for delivering their sites to users efficiently. The difference comes in how the Single-page application is built and managed...
React.js
React is a javascript library for building and maintaining Single-Page Applications.
But that's not even that big of a deal. The big deal about React is how it allows you to build applications...
Basically, you build things separately, then put them together: Components come together to form an Application. So take a look at this totally plausible but fake code for all the answers on this page:
answerArray.map(a => <Answer answerData={a}></Answer>)
This is one line that shows most of the information on this page. That is a big deal. The developers at Stack Overflow created their own component, called "Answer" and its only job is to show an Answer. You run that in a loop, and bam, all the intricacies of all the answers are abstracted, hidden in the Answer Component, which is completely separate from other components.
Now take a look at this:
<App>
<Header />
<LeftSidebar />
<Question>
{ answerArray.map(a => <Answer answerData={a} /> )}
</Question>
<RightSidebar />
<Footer/>
</App>
This is the whole Stack Overflow site.
Each tag (Header, Question, Answer, etc.) is a component. These components are completely separate and have self-contained code, but here they are used together to build the more complex application.
Composition
An important concept of React is composition, and we just defined it above. "Composition allows you to build more complex functionality by combining small and focused functions" (flaviocopes). Our Application is composed of smaller components.
It's also important to note that each component contains its own functionality. That means if the user clicks a button and a warning appears, the button and the code that makes the warning appear are in the same component.
Functional Programming
Surprise, we already defined this too. Functional programming, for our purposes, means 1. objects; and 2. how they behave; are in the same place. Like the button example above. Click a button, get a warning. And that's all in the same file.
This is different than pre-React development where all the buttons would be in one file, and all effects of the buttons would be in another. And this isn't necessarily a wrong way to do things, but for web development, it is easier to think in terms of self-contained building blocks, rather than widely dispersed tools that don't work by themselves.
Why you shouldn't care about Moustache and Handlebars
These two technologies have been cannibalized by React. Similar to how React uses AJAX but makes it easier, Moustache and Handlebars are already inside React, and you're using them all the time without even knowing it. And to me, that's ok. There are arguments to the contrary, and knowledge is never a bad thing, so investigate further if you want, but this is already long enough, so that's all I'll say about that.
Instead, I will tell you about 3 technologies you should care about.
What you should care about instead...
Node
The main point of Node.js is that it executes JavaScript outside a browser. Big whoop, right? Well, it turns out this is one of the most influential advancements for web developers ever. In fact, downloading Node is often done before downloading React.
Node is important for 2 huge reasons:
It lets you download other stuff
It lets you process JavaScript before sending it to a browser
I could write pages and pages about Node, but your takeaway from this should be "Node is important, I should be on the lookout for more knowledge about Node and how it relates to React and web development."
NPM
NPM does not stand for "Node Package Manager", but it should, because that's exactly what it does. React, SASS, Angular, Vue, pretty much everything mentioned here you will probably use npm to install and keep updated.
Webpack
Webpack is a "module bundler". It takes all your js and css files and writes them to one file so you only have to worry about writing one <script> tag.
Each React component will have at least one js file associated with it. Each component should have its own file too. Keeping track of all those files is very demanding. Webpack does it for you, it just makes life easier, so learn about it early and don't shy away from it.
This is something so inherent to React Apps that most of the time it will just be working and you won't even know it. For instance, create-react-app installs it automatically, and does not require you to do anything - same with Babel...
Babel
Translates all your code to ECMA5 so it can be read by most browsers and most versions of those browsers.
Again, this can be installed with npm, or if you just want to play around with React and not get too bogged down with the minutia like this, you can run create-react-app, and this will just work with automatic settings and will be out of your hair while you learn.
They make stuff easier
NPM, Webpack, Babel, and many other Node packages are only there to make your life easier. Building web apps require a lot of maintenance - or small, non-programming annoyances that typically you don't even need to think about.
Try not to be intimidated by new packages because wielding their power can mean countless hours devoted to more interesting things.
Conclusion
Hopefully, this post has helped you learn the difference between React, AJAX, and the ongoing nature of web application development. React and AJAX are not comparable, but React uses AJAX, or rather you - the developer - use AJAX in React to get data without the page needing to reload.
AJAX and other technologies were monumental to the advancement of web applications, but because of how absolutely essential they were to applications, they were assimilated into new technologies so much so that you don't even have to know about them to reap their benefits.
My goal was to correct some misconceptions on your path of learning; explain the "why" of the current state of web dev; and introduce technologies you didn't mention but should know about: Node, npm, Babel.
If you want to continue learning, I highly recommend doing a tutorial in React. I have done some at platform.ui.dev/, and enjoy their approach to learning and their payment structure (I haven't been paid to say this). Good luck out there, and I hope this was helpful.
Ajax is used to refresh a web page without having to reload it : it sends a request to the server, but typically the response is processed by the javascript that displays dynamically a new element on the browser without having to reload the entire page.
React is a javascript library that dynamically update the page with inferface components. The components are calculated either by javascript interactions or by an ajax request that go through the server. So ReactJS can also use Ajax requests to update the page.
Mustache and Handlebars are a bit different from ReactJS as the main goal is to transform a template in a component that will be displayed in a page. It can also use Ajax to get data (for getting templates or json datas).
Ajax
We are using Ajax to send http requests. And we can't re-render a particular area of the page(DOM) by using Ajax alone. We need jQuery to re-render the page after an ajax call came up with the response. Actually comparing jQuery + HTML and React.js is far better than comparing ajax and React.js.
React.js
The role of the react.js is dividing page(DOM) into small pieces (Components). ex:- Profile image area, Main Navigation, Sidebar, Textfield, Button. etc. from Big pieces to small pieces. Most importantly we can bind functionalities into these components. Example:- Let's assume users need a popup to upload a profile image by clicking on above "Profile image area". We can write a function to open a popup. And also we can write another function to upload profile image to the database. In this way we can use ajax inside the React.js
Please follow this tutorial.
To simply put, React is a JavaScript library built by Facebook. It is commonly looked as a framework because of its many extensions but the official docs label it as a library for building user interfaces. Ajax on the other hand is not a library or a framework or a language at all. Ajax is a technique used by programmers to call web APIs without having the flow of your code be interrupted at all. At the end of that day, your JavaScript code is run synchronously line by line and Ajax is run asynchronously within your synchronous code but in a way in which it will never pause your code from and have it wait for the API call to be sent and received. With Ajax, sending and receiving data is all done in the background so you won't have to worry about the delay that it takes to get that data. You can actually use Ajax in your React code. Ajax uses something called Fetch to actually call an API and you can use a variety of methods to handle the data that you receive from the API such as .then and .catch or Async/Await. You also aren't required to use Fetch at all, there are other third party ways of calling an API with Ajax such as by using Axios. I'd advise you to watch a video on how to use these different tools because when you figure out how they all work, you'll find that React and Ajax can be used together to build a great application. Hope this helped, please vote however way you felt about this answer. I'm pretty new to this website.
If you've scrolled down to this point you probably have this feeling of missing something in these answers which are great though. For me, it was hard to grasp what AJAX is. I had to look it up on Wikipedia. You can find a very good explanation there. I also read Jesse James Garrett archived article from 2005 where he coined this term (AJAX) and described it as a new approach to web applications. To dig deeper you can visit MDN.
Asynchronous requests are so obvious today in web development that it's hard to imagine there were websites without them. That's the key to understanding AJAX. At that time XMLHttpRequest API was something new. Now we have Fetch API in JavaScript or we could use Axios.
Google Maps approach was revolutionary in 2005. You could zoom in, grab a map, and scroll around. This instant response you had without page reloading was a result of the approach called AJAX. It consisted of a set of technologies like XMLHttpRequest, DOM, html & css, javascript.
As you can see AJAX is an old term to describe an approach in web development that makes applications more responsive (more than 20 years ago). Thus no matter what framework you use (Vue, Angular) or a library like React you use AJAX approach whenever your calls to API are asynchronous and they don't stop the user from interacting with your app which is a standard approach today.
BTW React is a library because it doesn't have a built-in state management tool, or routing tool in contrast to Ember.js, Angular, or Vue. We often talk about React stack, a set of separate tools for building react apps (Redux, Zustand, context api, react-router).
I am playing a Flash-only game that uses AJAX to communicate with the server. The problem is that all the data is "drawn" and most of it not copy/pastable, so I end up retyping URLs and similar stuff from parts of it (i.e., from the chat).
I thought I'd make a simple page action extension for Chrome that would intercept all the AJAX communication between the game and the server, the way Developer tools can do it, and display only the data I'm interested in (parsing URLs and similar stuff is a no-brainer).
However, looking around the internet, I've found no info on how to do this. Many sites (including answers to some questions here) mention using Developer Tools (I'd prefer having a page action extension, simple enough to share with other players, but any other automation is welcome as well), some mention chrome.webRequest (which seems to be able to provide only the headers),...
I also thought of making a content script along the lines of this answer, but since I'm trying to read the data between a Flash applet (not a web page) and a server, I don't think injecting a JavaScript code is possible.
So, my question is: can this be done and, if yes, how?
In case anyone got the wrong idea, the aim of this is only to monitor the communication and extract the parts I'd want to be able to copy/paste, not change any data (i.e., the purpose is simplification of the game play, not cheating).
I need for users to upload files (mostly images) without leaving the current webpage. What's the best tool, library or mechanism for doing this? I'm using the latest jQuery and Spring webmvc (with JSP), so if there's already a mechanism within them then that's ideal.
It would also be really great to have some kind of progress bar. Does that mean it requires coordination with the server to read the progress (where Spring would have to come into play)? Or is there a mechanism within JavaScript for this?
You should check out Plupload.
Plupload offers a cross-browser
JavaScript File uploading API that
handles multiple file uploads,
client-side progress meters, type
filtering and even client-side image
resizing and drag-and-drop from the
desktop. It achieves all of this by
providing backends for Flash,
Silverlight, Google Gears, HTML5 and
Browserplus and picking the most
capable available option.
Its really neat! Here's a link to some of their Demos...
http://www.plupload.com/example_jquery_ui.php
... and a screenshot of the jQuery UI queue widget (it has a progress bar!):
I hope this helps.
Hristo
I use uploadify pretty regularly: http://www.uploadify.com/
However it does use flash for the upload mechanism and as a result may create some issues if the user is authenticated.
You should use AJAX on the client side
http://www.webtoolkit.info/ajax-file-upload.html This tutorial covers all client side.
Om the server side
This tutorlal covers most of this issue:
http://www.ioncannon.net/programming/975/spring-3-file-upload-example/
Yopu can use jquery as well or any other JS framework.
But the mist important thing is the fact You need to remember that your tag on client side should have.
enctype='multipart/form-data'
property. it means that your request contains muultipart data.
Uploadify does that trick > http://www.uploadify.com/
All samples are php but you should be able to convert it to your platform.
I have no idea about AJAX programming features. I just know that it is Asynchronous Javascript and XML.
Please help me in knowing about this language.
I have gone through many AJAX tutorials. But none of the programs are running. Why I don't know.
Do we save the file with .HTML extension?
Read:
AJAX Tutorial by W3Schools.
AJAX Programming by Google Code University
To start coding you can get the Ajax Control Toolkit by Microsoft. You should read Ajax Control Toolkit Tutorials to get a grasp of it.
You can use the free Microsoft Visual Web Developer 2010 Express Edition as your IDE.
Aside from the correct responses that the others gave you, judging from your question I think you first need to learn about client-side and server-side code.
Do we save the file with .HTML extension?
Yes and no. You will have an HTML frontend, that for instance contains a button. This will be interpreted from the client's (=user) browser. In fact it may be rendered differently depending on the browser/OS/etc.
Now, you attach some Javascript code to this button. This also runs on the client's browser, and creates a XMLHttpRequest object, either directly or through the use of a library (JQuery & Co.). Note that a library is not necessary to do an AJAX request. It will make your life easier if you do a lot of AJAX calls, but it is not essential.
And here's where the magic happens: the XMLHttpRequest object will call asynchronously (i.e.: without reloading the page) a server-side page. This may be a PHP, ASP, Perl etc etc file that does something on the server, for instance queries a database. This part of the operation is absolutely independent from the client. The user can close the browser before the server-side code finishes to load and the server will not know about it.
Once the server-side code has finished executing it returns to the client with some response data (e.g. a piece of XML, JSON, HTML or whatever you like). Finally the client executes (or not) some other Javascript code in response to this, for example to write on the screen, again with no reloading of the page, something based on what the server has returned.
Maybe I can help you understand AJAX by clarifying the concepts a bit.
Please help me in knowing about this language.
AJAX is not a language, it is a way of using existing techniques to improve the user experience of a web site. The language is Javascript in the browser but you can use any server side technique that you feel comfortable with (ASP.NET, Java, PHP, Ruby etc.)
Do we save the file with .HTML extension?
Well, that is not really the point. What you have to grasp here is that there is a server and a browser that interact with each other. Yes, you can use static HTML files for your pages (and save them as .html files), but you'll need a server to respond to the requests of the browser. This may be why your sample code is not working; you need to set up a server that works with your pages.
The whole idea behind AJAX is to improve the user experience by not reloading the entire page when a user interacts with it. You request the data you need and update the page by using Javascript to update the HTML. This is called an out-of-band or asynchronous request.
I just know that it is Asynchronous Javascript and XML.
That is what the acronym stands for but it doesn't quite cover what the technique is for, nor is it accurate any more. In the beginning XML was used to transfer data from the server to the client. People found that XML is not really that easy to work with in Javascript so now it's more common to use JSON. JSON is a snippet of javascript that can be evaluated in the browser. The snippet creates javascript object(s) that represent the data.
If you use a Javascript library, like others have suggested here, you won't have to worry about many of the details though.
Before you get into AJAX you should make sure that you understand:
HTML and CSS
Javascript
how to modify HTML with Javascript
how a browser requests information from a server
how to handle requests on the server
If you are not comfortable with all of these concepts, stick with 'regular' web pages and try to improve your knowledge step by step.
Once you get the basic knowledge from W3school, I suggest you use a framework. Usually developers do not use XMLHttpRequest at all. Instead, javascript frameworks like ExtJS, jQuery and other frameworks make your work simple. I suggest you learn bit of javascript as well. check out jQuery.
Just to add that AJAX is rarely used in its pure form with XMLHttpRequest. You will often use it as a part of AJAX UI libraries which make your life easier. If you are from the Java world - such an AJAX library is Richfaces.
Instead of worrying about how to do AJAX, use something that allows you to forget about it. Frameworks like NOLOH do AJAX (and Comet) for you automatically without you having to do a thing. Just concentrate on your application, and business logic and it does the rest.
Really, everything is done via AJAX if available, automatically. No work on your part. If you're don't want to spend much time researching it, check out this short video that was demonstrated at Confoo PHP Conference this past March http://www.youtube.com/phpframework#p/u/11/cdD9hSuq7aw.
For all those worried about, well, if it's all AJAX, what about search engines? No need to worry, http://dev.noloh.com/#/articles/Search-Engine-Friendly/.
So instead of having to worry about all these different technologies, or the client-server relationship, you can sit down, code and have your website/WebApp working in no time.
You can read about NOLOH is this month's cover story of php|architect magazine, http://www.phparch.com/magazine/2010/may/.
Enjoy.
Disclaimer: I'm a co-founder of NOLOH.
It is easy one. Ajax getting data from server side by client side execution. We have to do use XMLHttpRequest to get the result.
I need to understand a good way to design a web page with dynamically updated graphs. It should be something close to what stock market graphs look like (e.g. Google Finance), although with a bit more complicated functionality, which is not the point. Naturally I am thinking of writing an ajaxy-style flash control, which would communicate with the server through, okay, something like XMLHttpRequest, but from within flash code, and draw things basing on data received. Is this doable with flash? Does security model allow such kind of client-server interaction? If yes, could you think of any references for me to get started (similar opensource projects, articles, whatever)? Or should I forget about flash and use a Java applet right away?
An important thing to note: I don't think I can use Google charting API, because I need also to have user interaction. In the link above to Google Finance the user can drag the graph to and forth with the mouse, that's close to what I need (I will also need to implement some actions from the dropdown menu).
Thanks for your answers and opinions!
Try this: JQuery Flot
Flot is a JQuery plugin to plot graphs. You keep replotting in-place with the latest data at the desired frequency to generate a dynamically updated graph. It is based on the <canvas> tag. We use it successfully to generate pretty complex dynamically updated graphs in our applications. The updates are fetched via periodic AJAX calls.
Another alternative is YUI Charts
We did not explore this a lot but this uses Flash and AJAX like you wanted to do.
/RS
I have used the Google Charts API to do this sort of thing. For a simple example, see my Sunrise and Sunset page. This page calculates sunrise and sunset times for a given latitude and longitude, all in Javascript, then uses the Google Chart API to replace the graph on the page with the requested data.
Update: The Stack Overflow reputation graph (see your user page) isn't Flash and yet allows interactive dragging. (Click and drag on the left to update the posts on the right that reflect the highlighted reputation region.) Perhaps you could look at how that is implemented.
You have described Flex...
This is very possible in flash.
You can use the URLLoader class to obtain data from a server at run time and the draw your graph using a custom control. In actionscript3 you'd subclass the Shape class and write a little drawing code to draw your graphs. Flash has support for drawing and filling so it would probably be very good at this.
The flash client can poll the server for updates. Or if you want a "live" connection you can establish a socket connection to the server and let the server push updated data live. Flash is good for this as you can push XML data over the socket and use the built in support for processing the XML, or you can send binary data just as easily.
As for the security model it's just the standard flash one. You can make network connections back to the server that the swf file came from with no issues. If you want to make a connection to a different server then that server needs to give your client permission to connect to it by hosting a crossdomain.xml file
I'm not sure about the Flash side of things, but this would be pretty simple to do in Silverlight. I am pretty sure you'd easily be able to make a server request in Flash too.
I'd do some searching for long polling.