HTML5 executing query without postback - javascript

I am using html5, javascript and JSP for my project. I want to know if there is some method that i can used to execute a query from my servlet without actually posting back the page. i know it can be done in ASP.net but i do n't how it can be be done in java script and JSP. Actually i have a dynamic webpage displaying data from server.what i want is that in a click event of button i want to execute a query form server and update it on the page. i know i can submit the form but it will submit the page which i want to avoid.Any suggestion......
regards
nquazi

You can use an AJAX request to submit inputs and get back an output without reloading that page. Here is a previous stackoverflow answer that shows you how to do a HTTP GET request.
HTTP GET request in JavaScript?
You will then need to process your inputs, run the query, and send back an output on the backend server.

Related

Can I use post to click a button on a page in JQuery?

I'm trying to request a page and click a button on it without opening a window so I'm thinking post could work. Here is my code:
<!DOCTYPE html>
<html>
<head>
<title>test</title>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"</script>
<script>
$(document).ready(function() {
$.post(
"http://m.roblox.com/Catalog/VerifyPurchase?assetid=161075864&type=tickets&expectedPrice=1",
$("ui-block-a").submit();
);
alert("work");
});
</script>
</head>
<body>
</body>
</html>
If I'm understanding post correctly, the first argument is the url to which it requests from and the second argument is the one where you can send data. I'm trying to send a request to click the "buy" button on the page if you follow the link. Can anyone help?
A post request sends data to a given URL. What the server does with that data from that point is entirely up to the server. It is very unlikely that the web page you are trying to simulate a button press on allows that behavior. If that was possible in general, it would leave users open to some very large security vulnerabilities. For example, a site could simulate donating money via PayPal without the user ever knowing.
In this particular case, the button appears to submit a form. In that case, you could always attempt to send the request directly to the page that the form submits to, which would simulate submitting the form. However form submissions are generally protected against stuff like this, because again, it could be used to act on behalf of the user.
Basically, the best option for something like this is to provide the user with instructions detailing what they need to do, and then open the page for them.
Assuming there is no other issues like CORS you can do the post like you are trying to do, but the following is invalid.
$.post( "http://m.roblox.com/Catalog/VerifyPurchase?assetid=161075864&type=tickets&expectedPrice=1", $("ui-block-a").submit();
You are doing a POST which required the data being send to the server to be in the request body and not the URL string.
When you post to a page you are actually posting directly to the server and not a page and in this case unless the $("ui-block-a").submit(); is returning data for the page you are posting to, it is not needed.
The following would be closer to what you are looking for with that post
$.post( "http://m.roblox.com/Catalog/VerifyPurchase", { assetid: "161075864", type: "2pticketsm", expectedPrice: "1" } );
If it was successful you should see a allow-orgins error in your developer / inspector console.
$.post() is an abbreviated form of $.ajax(), with POST pre-selected as type. There are also $.get() (with GET pre-selected as type), and $.load() (with the returned data immediately injected into the specified element). But $.ajax() is the grand-daddy of them all.
AJAX is a method of exchanging data with a processor file on a server, without leaving / refreshing the page you are on. That is, with AJAX (or $.post), you can send information to a processing page on the server -- such as: my_processor.php -- the processing page can do something with the data (for example, use the data to query a database), and then echo out data, which is returned to the originating page. The received data can then be injected into a DIV on the original page, or something of the sort.
An ajax routine is usually triggered by some event on the originating page (the user presses a button, or selects a value in a drop-down, or some such). Javascript (or jQuery) code detects the event, and the AJAX code is usually actioned in the javascript event.
Here are some simple examples of what has been described.

How to pass javascript variables to rails variables

How can I pass a javaScript variable into ruby. I want to do something like this but I don't know how to express it.
function save(){
var g = document.getElementById("self").value;
<% #owner.info = g %>
}
Another possible work around is that i would need to be able to extract contents of a text area through rails and not javascript.
Can anyone help me?
What you are attempting to do doesn't make sense with a vanilla rails installation and javascript. Here's a good workflow that accomplishes what you're trying to do along with some details:
1. A page is requested from the server
The ruby code that runs rails and your application is executed on the server. The server receives a request, executes the ruby code, and sends the response as an html document.
2. A user gets the response from the server
The user's browser receives the html and turns it into a pretty web page. It's at this point that any javascript related to your application is executed in the user's browser. The connection with the server has been severed and no further ruby code will be executed until another request is made.
3. The user fills out an ajax form
On the page rendered in step 2, you have a form. Following this guide you can tell this form to submit via ajax. That means instead of requesting a new web page, the browser will send a special request using javascript to the server. The server can save the form values to your database and send a response back to the browser. All the while the user hasn't left the page they are currently viewing.
Alternatively you can skip the ajax and have the user submit the form, but you'll need to redirect them back to the page they were viewing (and probably adding a note the form they submitted was saved).

ajax post big data Jquery

I am facing problem for sending big form data using ajax function to server i.e php page. In my page html input fields will add by users for making a quote. And user add many fields then all datas wont posted to server php page. Only some information will save in database and others will lost.
I have used post method in ajax function.
If you have any suggestion for this problem please suggest me.
Detect place of the problem
Check POST request. Did you see there your data. In case you see - there is only one reason some where on the server. It couldn't be limit of the post - because in this case you will never get any information on the server and all request would be cancelled.
Another place is in your javascript:
1. you make mistake in name of field
2. bug some where in library
3. bug in your code.
try to debug javascript and understand what happen there.

How to get POST contents before form submits using javascript

So, I know that when I submit a form whose method is POST that the server receives the contents of that form and then processes them accordingly, and then returns a page with the desired content. What I am trying to learn is what exact query url is being passed to the server side script when I submit a form on a website that does not belong to me. The reason I want this query string is so that I can make use of the server side script programatically with my own data. There is no public API served by this website, but I would like to formulate my own.
So my question is, is there a way to intercept the POST as a query string URL? Perhaps by using a javascript console in browser?
I know I can look at the source code for the page and find the names/values of the form fields. However, there also happens to be a hidden field on this page whose properties are set by javascript during validation at submission time. How should I go about this?
You can use an extension for intercept the data : Tamper Data on FireFox
https://addons.mozilla.org/fr/firefox/addon/tamper-data/
You can intercept and modify all headers requests

Ajax, Javascript, or Database for post/get results

I have a question about what backend to use. I have a html page that has various dropdown lists. On Submit I want to sent the results of that page to another page to compile the (average) results. Is there a way to do this without setting up a database? I was thinking of sending the data with Ajax and then compiling the data with Javascript on the receiving page.
I've done something like this before so any suggestions would be appreciated.
You can use jquery to check the changes in the dropdown list. Send the results to a jquery ajax page and get the return value as json. The result json can be shown on the same page with jquery.
I assume the page you are talking about is an html or jsp page. Yes you can use javascript ot process the data and then send it to a servlet and get it back to another jsp.

Categories