I am trying to write a Perl script that will take a user parameter from command line and with his parameter, Perl script will call a JavaScript function in a HTML page. How can I go ahead to with this?
Not that I've seen. Perl is strictly server side, and JS functions you're talking about are on the client.
The closest you would get is have the Perl script write a block into the HTML page so that the page fires it on load to perform the action. But that's a little shaky at best to do.
It depends on whether the browser or server will be taking the first step.
If the server needs to run code first and then execute some JS, then #skyburner's solution would work. Essentially you would already have some functions defined on the page, but then you would dynamically add a block of JS to call whichever function you need to.
However, if the Perl is being run due to a user's action on the current page (such as clicking something or submitting a form), then AJAX would be the way to go. You would use JS to submit an HTTP request to the Perl script. The Perl would then return some value back to the JavaScript and execute some function based on this result. This would all happen "behind-the-scenes" without the user leaving the page.
If I understand correctly about what you want, since not all the browsers support socket, this is what you can do:
Have an ajax service call periodically sending requests to the server for update
Once the the parameters from the command line are taken, you can send the result along with an ajax response back to the page, and call the function in the ajax request callback function.
Also, another option, you can use reverse ajax to accomplish this. See Wikipedia about reverse ajax (comet), especially Ajax with long polling.
Related
I have an AJAX call that is running a long PHP script where it has 20 different results, I would like to show when each step in the script is done.
Like so 1/20 done, 2/20 done, 3/20 done.
Latest 29-12-2015 03:17.
I tried to create the JSON file as so (jsonFileName_uniqueTimeStampHere.json) by PHP, but the time taken to create the file with PHP, result in a 404 file not found error!
Because when the AJAX call is running it comes to the progress call before the file has been created, I know I can't create the file with JavaScript but is there anyway to create.
The file before the success callback from jQuery AJAX?
What would be the best way to show progress information while AJAX call is running.
The way I have it now, I have a JSON file saved on the server that gets updated with the latest state that has completed, but if multiple users is running the same script the JSON file with the state gets overwritten.
Should I save the state of each progress in DB and then receive it with multiple calls to a PHP method that get state that has been completed?
Should I keep using the current method I use and add a userID to the JSON file so it is unique on each call to the file?
How should I go about doing it the same way as Seositecheckup?
What is the best way to make a progress with AJAX and PHP?
Please tell me if you need any more information.
I have looked around and don't feel like the info or half of info, there is to find online has been enough to do this myself.
I would like to use jQuery AJAX and not XMLHttpRequest, I'm looking for something similar to seositecheckup.com, when you scan a page you can see the state update on each completed function in the console and is done with different AJAX calls. How is that possible?
Should I forget about using jQuery and keep focus on plain JavaScript instead?
Right now I have a setup with jQuery that works the problem is, that I use a JSON file to get the result from and it gets overwritten when multiple users request the same script, is it possible to store the state in db instead and receive it from there with some unique identifier?
In the future I would like to make it possible to put the script into a queue that could be run and when the script ends it should send an e-mail to the user.
The HTTP way of handling requests that may take a long time is for requests to return a 202 and the body of the response should contain the URL where the user can query for the result.
#Request
POST /some/entitities
...
#Response
HTTP/1.0 202 Accepted
/jobs/{jobId}
The user can then poll /jobs/{jobId} which can return a number to represent progress. Do you have to use this? No, but if you do, others developers can immediately recognize what is going on.
Even if you don't use the approach I recommend, you will also have to keep track of job progress in your database and have a separate AJAX call to find out the current progress.
I need a simple way to call a URL to send a command to the system without processing or displaying whatever result is returned. If I use simple HTML calls then the frame the page with the button is on changes to the result returned by my lighting system and my page of buttons goes away. If I use ajax then I run into cross domain issues.
At it's simplest I would just like to have a button process an onclick() and execute a URL (e.g. http://www.mydomain.com/lightingdevice/on) in the background or some simple javascript that runs this same URL while the frame continues to display the page with the button.
Either way you need to use AJAX if you need to do this discretely.
The interface is on the same domain as your application: just use AJAX properly and you're good.
The interface is on some another domain as your application: create an interface on the same domain as your application, using PHP for example. This will let you use AJAX. Then just let PHP handle all the rest.
The clearest example of this I could think of is the Reddit Upvote/downvote buttons how when you click the button, the value for upvotes is updated, the upvote button lights up, and the page DOES NOT reload, you just stay exactly where you are on the page.
I am trying to make a feature similar to this and I can totally figure out how to do it with reloading, but I want it to not reload so the user experience isn't disrupted.
Is it possible to do this with php? or would I need to use javascript or something?
The action I would need it to perform would be a basic update query in the database.
This would be done with an Ajax call to your php script. Ajax is designed for these asynchronous updates and/or reloads.
Another way you can do this is with HTML5 WebSockets. You could have the client send a trigger to the server when the user clicks the upvote, and then the server could update and push back the data. It would, however, be a bit overfill for this.
If what you want to do is to contact a server to either send it some state or to retrieve some state from the server (or both), then you would use AJAX with javascript in order to contact the server without reloading the page. You can then also use javascript to update the state of your page after the operation. That is generally what the Reddit page you refer to is doing.
Conceptually, you'd set up your page like this:
Put the link on the page.
With javascript install an event handler so you are notified of a click on the link.
When the link is clicked, your event handler will be called.
Prevent the default behavior of the link so the browser doesn't navigate to a new page.
Then, in the event handler, send your data to the server using AJAX. You will obviously need a URL on your server and server process that can accept and process the data for you and return a value if you need to.
If you need the response from the server, then set up a callback function for when the AJAX call completes (this will be some indeterminate time in the future).
Then, if you need to change the current page in any way (like show one more upvote), then you can modify the current page with javascript to show that new state.
Ajax is easier to use with a library (like jQuery) that contains some ajax support code, but you can certainly implement it in plain javascript too.
Here's one example of ajax with plain javscript. You can find many other examples with Google.
This MDN tutorial on AJAX seems pretty helpful too to show you how it works.
You could use JavaScript to do this. Here's a quick sample:
Vote Up
Simple solution in JavaScript:
var el = document.getElementById("upvoteBtn");
el.addEventListener("click", onVoteClick);
function onVoteClick(e) {
e.preventDefault();
// do something
}
Here's a fiddle.
NOTE: I see you'd be updating the database. In that case, you would have to use AJAX in the onVoteClick function (or use XMLHttpRequest) for this. JavaScript is a client-side programming language and will not be able to communicate to the server without the use of AJAX or XMLHttpRequest. Using the jQuery library, you should be able to write AJAX pretty easy.
It's called AJAX.
With AJAX you can send a request in the background.
The easiest way is to use the jquery libary for this.
You can also output some data as JSON back to the script if you want to take some other actions depending on the result from that query.
A good tutorial is this one.
It also explains how this requests (called: XMLHttpRequest) work.
You need to use Javascript's XMLHttpRequest
You can use AJAX...
It allows you to use JavaScript (client side) to call server side functions. Here's a good example.
I noticed that when a link on the page has JS onclick function and also a MVC action method, the JS function fires before the action.
Wondering is this always the case?
Why/how browsers deside to run JS and the the backend method?
Can I run backend method first, but still want to fire the JS function?
Regards
Wondering is this always the case?
Why/how browsers deside to run JS and the the backend method?
Client-side JavaScript runs on the client, inside a page. Server-side .NET code runs on the server and generates an HTML document (or other resource).
To run server side code, the browser has to make an HTTP request.
The easiest way to make an HTTP request is to leave the current page and load a new one from the server (by following a link or submitting a form).
Since client-side JavaScript runs in a page, it can't run after the browser has left the page it runs in.
Can I run backend method first, but still want to fire the JS function?
You can make an HTTP request from JavaScript (before doing other JS actions) instead of leaving the current page. This is usually done with the XMLHttpRequest object and is known as Ajax.
Why/how browsers deside to run JS and the the backend method?
server side code will need a request to return the response. HTTP works on Request and Response architecture. basically client make requests in order to get the response (i.e results or desired data)
wheenever you do postback or return true to the server, it will execute server side methods.
ClickHereToSee
here return value which is returned by the function, if you return the true value it will go to the server method, if you returned the false it will prevent the default action.
Can I run backend method first, but still want to fire the JS function?
You can. use Ajax. basically Ajax requests are XMLHTTPRequest. which used to update the paritial portions.
Can I run backend method first, but still want to fire the JS function?
First two answers are already well answered. For third one you can try Jquery Ajax-
function SomeFunction(){
$.ajax({
type: 'POST',
url: "#Url.Content("Controller/ActionResult")",
data : {
*yourparameter:value* //data
},
dataType: 'json',
success:function(result)
{
//javascript stuff
}
});
}
ClickHereToSee
Since mostly a backend guy, I am not sure how can I achieve the following since it
requires some interaction with the browser.
So, I have a the following things so far.
A communication protocol where server is in python and client is in javascript code.
Ultimately, I want my data to reach to that javascript code.
Now, this data is being captured from browser.
As a practice.. what I am trying to do is.. have two radio buttons on my browser and a submit button
*radio A
*radio B
* Submit
Now, when the user presses submit, I somehow want to create a query "user submitted: A (or B)" and this query i am able to capture on python script.
I am at lost on how to do this.
My guess is that "submit" invokes a python script.
But what if my python server is always on .. how do i parse that response from the click of browser to this python server?
This is the way it usually works:
Client (browser) visits webpage and initiates request to server
Server (in your case, Python) handles request and writes HTML response, including the radio-button form
Client fills out form and hits Submit, triggering another request to the server
Server handles the second request and writes another response (e.g. "Purchase successful", "message posted", etc.).
Note that the second request is a brand-new request. You may want some way of linking the first request to the second one unless the second request is anonymous. Some frameworks will do that for you, but if you are making the server from the ground up you'll want some kind of session mechanism to keep track of state.
To get the client to make the second request, the simplest is to add appropriate action and method attributes to the form element in your HTML. action specifies the URL to access for the form request, and method is either GET or POST. (More advanced usage, e.g. on this site, typically uses AJAX to make the submissions instead).