I recently wrote a PHP wrapper class for a new API we are using and have been asked to setup a demo which makes use of it. Certain features can be called directly from PHP, however things such as performing actions on button clicks requires I make use of JS/AJAX.
As I already have an instance of the object in my main PHP file, can I pass this as a parameter to JS and then pass it through Ajax to my handler or is it necessary to establish two separate instances?
The closest thing to doing what you want that I can think of would be copying the PHP object to a JavaScript variable via json_encode and then passing that variable back to your PHP code during the AJAX event via the data parameter. PHP code doesn't persist in the way that you seem to be describing - once a page has been requested by a browser, your PHP code for that page is done, there are no variables persisted by the server after that point.
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I made a nodejs application that starts from index.js.
Then, index.js launches puppeteer and injects bot.js on a headless-api page by addscripttag function.
I made index.js sets a cookie for conveying initial values before injecting javascript, but I need more common way to exchange data.
I thought two ways; the first is using cookie, and the second is networking via socket connection.
Is there other way for send and receive data between index.js(node) and puppeteer(headless chrome)?
First, puppeteer IS nodejs side application, so they have a single environment and you don't need to "send" anything. Just pass data around as you'd do in any other JS code. I assume you want to transfer data between page and nodejs then.
To pass data from nodejs to page use page.evaluate. You can call any code in page context, ranging from simply setting some variables to directly calling whatever functions with necessary arguments.
To initiate transfer from page side to nodejs, first register a nodejs-side callback function with page.exposeFunction and then call it from page code and it will be executed in nodejs context. Just like in previous case, everything else depends on code of that function. It can be as simple as storing whatever argument you pass to it in some variable or directly perform with data pretty much whatever you want.
I've seen a servlet between the JSP and the database that is implemented similar this page. the important part for me is this:
param p1fd = new param();
p1fd.setVal(request.getParameter("formDDL"));
where the parameter in jsp code is referenced as "#formDDL"
the problem is that I have formDDL as a javascript variable as such:
var formDDL;
How can I convert the javascript variable to #formDDL?
Is there any other way to I pass this variable to Expression Language written for inserting in mySQL code?
The scriptlet part of the JSP is executed on the server side prior to it being returned to the client. Therefore you can't change its value after the page is sent to the client. You would have to have a preliminary page that sets the value of formDDL in javascript and then call into the server to request the page with the formDDL included as a request parameter or POST data. Basically the same approach that was done in the page you linked.
If you didn't want to have to fully reload the page to change the value of formDDL then you would have to take a completely different approach and look into using Ajax.
Also be mindful of SQL injection attacks when following a similar approach to the one you linked to.
I'm trying to use a JS variable inside of php code that executes a function. Based on the selected radio button, Javascript gets a string of code from a data attribute of the radio button (trimcode) and I need to set this as the key in my PHP function where one of the variables requires an array key.
The result will be, whenever a radio button is selected, the PHP function inside this function will execute using the 'code' variable and thus return it's return value as the inside content of the "byo" class div via javascript innerhtml. However, I can't figure out how to use a javascript variable inside of PHP code that is inside another javascript variable. Can someone point me in the right direction?
<script type='text/javascript'>
$(document).ready(function(){
var code;
var colorsavailable;
$("input:radio[name=trimlevel]").click(function() {
code = $(this).data("trimcode");
colorsavailable = ("<?=byoTrimImageColors($modelMap["+code+"],$hexcolors)?>");
$('#byo').html(colorsavailable);
});
});
});
</script>
I think you're confusing the notions of server-side code and client-side code.
The PHP code runs once, in its entirety, when the page is requested. Then, after it's executed, the resulting page is sent to the browser where the JavaScript code runs. And that line of PHP code isn't going to execute for each click event. It's going to execute once, and only once, and emit only one result to the page.
Given what it looks like you're trying to do, you probably have two options:
Include the functionality you're invoking in JavaScript code and just invoke it there instead of in PHP code. Whatever that array is, whatever that function is, implement those in JavaScript. Then there's no need to involve PHP at all.
If the functionality needs to be in server-side code, then you're going to need to use AJAX to invoke it. Essentially you'd create a separate PHP "page" (which emits JSON data, not an actual page) to accept the value, invoke the functionality, and emit the result. The JavaScript code would make an AJAX request to that resource and use the result.
Client-side, that AJAX call might look something like this:
code = $(this).data("trimcode");
$.post('someNewPage.php', { code : code }, function (result) {
$('#byo').html(result);
});
Server-side (and I'm mostly guessing here), someNewPage.php might have something like:
$code = $_POST['code'];
// you'll want to sanitize the $code value here, since it's user input
$result = byoTrimImageColors($modelMap[$code],$hexcolors);
echo json_encode($result);
Your idea is not possible since for PHP code to execute it requires a page refresh. The best solution would be using Ajax to send the data to PHP asynchronously and changing your HTML, using JS, with the data that comes back from PHP.
To learn how Ajax/PHP works visit this site: http://www.w3schools.com/php/php_ajax_php.asp.
It is not possible to call a PHP function from Javascript. PHP is a pre-processor and ALL PHP code will finish executing before the page loads. Once the page loads, the browser will load your Javascript files and JS will take it from there.
In order to "call a PHP function" again after the page has loaded, you will need to make a new request to the page. This is typically handled in Javascript via AJAX. Using ajax, Javascript can send a new request to the server, PHP will read it and send a response back to Javascript.
If you really need that PHP function to execute on the Javascript level synchronously, then consider porting that function to Javascript.
Right now what you are doing is constructing a string that resembles some PHP code. It looks like you are doing that part just fine.
However, you cannot execute PHP code on the client side. There is no interpreter available on the client (the browser) that knows what to do with your PHP code.
What I would recommend doing is if you need to run some PHP code, create a controller method or some script that you can execute on the server, make an AJAX request to that (passing the JS code variable), have the PHP method return the value of your byoTrimImageColors method, and then handle that data however you please.
I would like to give some values to my client (to use them in javascript) from my django server.
I know that I can use cookies, but the problem is that they are kept for all request whereas I need them only once when the client loads for the first time (it is not really a problem).
I could also pass those values to the template to render some html tags with the "data-value-name" properties set the the values (for example <body data-name="joe" data-id="123456">)
Both solutions work fine, but is there a better method?
What I usually do is to create a <script> element where I render the values directly to JavaScript objects stored in local or global variables.
If you have a lot of values you can also consider implementing a view that returns JSON which is requested via ajax from the client.
I have a javascript function where in one part, I perform an AJAX call and store some information.
In the same function, I move to a new HTML file.
window.location.href = "deals.html";
Once moving to the new deals.html file, how can I access the information I stored earlier?
Thank you for your help.
The information you stored using AJAX function resides in server now, you have to initiate another AJAX function to retrieve that information from the server when you get the new page.
You can write a javascript function to keep the data using cookies and access it in next page. This will be executed just befor redirecting to another page.
There is something called localStorage which is supported by latest browsers, you can use that to store response from first call, and use it second page.
This can only be achieved if you use cookies in JavaScript because, as you are navigating to another html document you loose the status of all the variables in the already executed script.
So before navigating away to another page set as many cookies as required.
References on cookies