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'm looking for a way to send data from processing to a web browser, specifically, I'm looking for a way to send data to Three.js and display it visually, but I'm a little stumped at the moment.
There are two main Processing ports in javascript: ProcessingJS and the more recent p5.js.
The p5.js port should be pretty easy to integrate: check out this wiki article on js libraries
It depends on experience and personal preference: you should totally be able to integrate using either of them.
p5.js is plain vanilla javascript so no problem integrating, but you need to be mindful about Processing syntax and the p5.js equivalent.
Processing.js should allow you to keep most of your Processing (java looking) syntax as is, but you'll need to get a reference to the Processing.js sketch from JS to integrate with three.js. Be sure to check Pomax's Guide to Processing.js for more in depth notes and if you're using the JavaScript mode in the Processing IDE also see the Environment and HTML5 examples.
Update
There's a chance you're simply looking for a way to send data/variables from an existing Processing sketch to the browser, in which case websockets is the way to go. You Processing sketch will also need to become a websocket server (which it can do via a java library), then your three.js webpage would become a websocket client. Check out this answer for more details.
Why not just use Processing to visualize the LEDs? If you are using Processing already for the lighting logic, just visualize it there, no need for a browser or Three.js.
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).
Ever since I've started asp.net mvc development my experience is almost 80% jQuery, only 20% C#.
Now I am begginning to use Knockout.js to enable myself to better control view on the page.
The question I am now facing is: should I be feeding the browser the "sceleton markup page" and load all data via ajax call, which in turn populates a js viewmodel object and therefore the view, or should I initially populate data via a partial view, and use js page data management for subsequent client experience?
Right now I am doing the latter, but this requires me to write two data retrieval/display logic - one in js, one in mvc razor view.
I am not planning to support browsers with js disabled, so maybe I should do everything via js knockout view model initialization?
There are many additional variables.
How many request per second should your app handle in future? If many, then with full page generation maybe you can cache resulting web page, decreasing load on server.
What kind of clients do you have? If they are slow (like low cost mobile phones), then generating full HTML on client can be slow.
Do your clients appreciate fast response over slow network? With full server page generation you can achieve smaller number of requests and faster response.
On the opposite side, if this is an internal department level business app with good network, low number of requests and good client computers, then you can surely go with minimal initial page and populating everything with AJAX. Also, as Arbiter pointed out, JSON can be smaller in size than HTML, so if you have a big amount of data then you can save on network via JSON.
There is also a middle third way. You can generate JSON data and embed them directly in the webpage (like <script>CallMyJSGenerateMethod({generatedJSON: "goes here"})</script>). This way you'd have only one (JavaScript) procedure for HTML generation, small number of requests (with even lower amount of data) and ability to cache web page. Still, you'd have to have a good clients, so point 2 still stands.
This is more of an opinion, but in my estimation, its the most oft asked question I get regarding building web apps: do I build the pages with HTML/MVC on the server or do I use all JS? There is no clear right answer here that fits all scenarios. Both are great choices. Dmitry's points are all valid, too.
Other things to consider are whether you need to stick with ASP.NET on the server or if other server tech will be used (PHP?). What skills does your dev team have? Will the pages you are creating change a lot on the client, or are they relatively static?
I personally lean towards the client space instead of server side generation, but its mostly a preference.
I'm still pretty new to AJAX and javascript, but I'm getting there slowly.
I have a web-based application that relies heavily on mySQL and there are individual user accounts that are accessed and the UI is populated with user specific data.
I'm working on getting rid of a tabbed navigation bar that currently loads new pages because all that changes from page to page is information within one box.
The thing is that box needs to reload info from the database, etc.
I have had great help from users here showing that I need to call the database within the php page that ajax is calling.
OK-so pardon the lengthy intro-what I'm wondering is are there any specific limitations to what ajax can call that I need to know about? IE: someone mentioned that it's best not to call script files and that I should remove scripts from the php page that is being called and keep those in the 'parent' page. Any other things like this I need to keep in mind?
To clarify: I'm not looking to discuss the merits/drawbacks of the technology. I'm wondering about specific coding implementation that I need to be aware of (for example-I didn't until yesterday realize that if even if I had established a mySQL connection on the page, that I would need to re establish that connection in my called page as well...makes perfect sense now).
XMLHttpRequest which powers ajax has a number of limitations. I recommend brushing up on the same origin policy. This is a pivotal rule because it limits where AJAX calls can be made.
First, you can't have Javascript embedded in the HTTP response to an AJAX call. That's a security issue.
No mention of the dynamics of the database, but if the data to be displayed in tabs doesn't have to be real-time, why not cache it server-side?
I find that like any other protocol, Ajax works best in tightly controlled conditions. It wouldn't make much sense for updating nearly the whole page, unless you find that the user experience is improved with an on-page 'loader'. Without going into workarounds, disadvantages will include losing the browser back button / history, issues such as the one your friend mentioned, and also embedded resources and other rich content can suffer as well, and just having an extra layer of complexity to deal with in your app. Don't treat it as magic sauce for your app - make sure every use delivers specific results that benefit your client / audience.
IMHO, it's best to put your client side javascript in a separate page and then import it - neater container. one thing I've faced before is how to call xml back which contains code to run such as more javascript - it's worth checking if this is likely earlier on and avoiding, than having to look at evals.
Mildly interesting.