I'm using the following code to get the screen resolution.
This works fine with WAMP server but when I put it on the remote Linux server, $height returns 0 .
HTML/PHP
<head>
....
<script language="javascript">
var y=window.screen.availHeight;
var x=window.screen.availWidth;
window.location.href = "index.php?height=" + y + "&width=" + x;
break;
</head>
<?php
$height=$_GET['height'];
$height=intval($height);
echo($height);
?>
You may want to explain what you are trying to do with this webpage, give an overall explanation of passing in the height to php, because this page is not working at all.
This is the execution flow that occurs with this web page.
User enters index.php in address bar.
PHP Server handles the request.
The $_GET array will not contain a height parameter.
$height will contain no value.
calling intval($height) when $height is empty will return 0.
The page will load, 0 will be displayed.
JavaScript is executed.
The URL will be constructed with the height and width parameters.
Browser will throw an error: Uncaught SyntaxError: Illegal break statement
Execution ends.
PHP is server side. It receives a request from your browser and renders the HTML/CSS/Javascript output before sending it back to your browser. Thus, any information about your browser size or screen size needs to be sent to the server as some kind of request, either when you first open the page, or after you've loaded the page. Sending a request to the server after you've loaded a page is called AJAX, and that's most probably how you'll have to do it.
http://w3schools.com/ajax/default.asp
You can do this via AJAX, but you will need to send the data to a different PHP file and do the processing there (which should work out alright, since PHP is processed on the server and not on your computer.
AJAX works like this:
In javascript/jQuery, put some value into a variable
Create an AJAX code block (I recommend using the $.ajax() structure at first)
In the AJAX code block, send the var-value pair to the PHP file
PHP file receives the variable-value, and does something with it
PHP can return some data (usually a string of HTML, like a table, etc)
Data from PHP is received in the SUCCESS function of the AJAX code block
Inside SUCCESS function, you can inject received code into the DOM
Here are a couple of examples (it's actually a LOT easier than it sounds/appears at first glance):
Sending value of dropdown to PHP page
Another basic AJAX example
Related
I am trying to write a plug-in for firefox which would fetch all the domains from the links of the current site and display their IP addresses.
for that I have written js code containing "domians". And simple php script:
<?php
$ip = gethostbyname('www.example.com');
echo $ip;
?>
now i have to pass this "domains" array to php and return the ip values to js code in order to display the domains with ip(s).how can i do this?
I heard that ajax, json can do this. Is there is any other possible solution?
From what I understand, PHP is executed server side. This means that when the user load the plug-in/page/content, the PHP is executed and done with. This being said, JavaScript is executed Client side, meaning it can be executed during the page load, before the page load and after the page load. Unfortunately this means that you cannot pass JavaScript variables to PHP without using AJAX or going to another page.
The way you would pass information from JS to PHP would be by receiving the data you need, then making an Ajax request to a PHP script that would perform some action and then return some value. If that's what you want to do, then there are tutorials/many questions that will help you in doing that.
To pass from PHP to JS, you can do something like:
<script>
var JavascriptVariable = <?php echo $PHPVariable ?>;
</script>
But this might be bad practice, I am unsure.
The code looks like this:
PHP file
<?php
...
$arrayName = ['ArrayValue_0', ..., 'ArrayValue_n'];
...
php?>
JavaScript
$('.elementClass').each(function(index, id) {
$(id).html('<?php echo $arrayName[index - 1]?>');
});
But you can't just insert a JavaScript variable like that into php tags so index is never received.
I know this can be done via AJAX but is there any other way? Thanks in advance.
Additional info:
I've been told to do this in PHP so there's no posibility of switching the array to a JS file.
You can define arrayName variable in JS and initialize it with the value from the server:
var arrayName = <?php echo json_encode($arrayName); ?>;
$(".elementClass").each(function(index, id) {
$(id).html(arrayName[index-1]);
});
What you're trying to do will not work. For example this:
$(id).html('<?php echo $arrayName[index - 1]?>');
The above will never, ever work, because PHP is run on a server, not on your user's browser.
What you need to do is send the variable somehow to the server. You have a plethora of options:
Use a form and read a $_POST variable
Append it to a URL and read a $_GET variable
Use AJAX and asynchronously send that variable to the server
Return the whole array from PHP to your Javascript code
etc. etc.
Remember, PHP runs on the server, which renders the page, which then in turn is read by your browser where you run Javascript. You can't paste PHP code into the page and expect it to be parsed by PHP!
You need to get back to the server if you wish to get info from it (PhP runs on the server), so either you create a javascript variable on-the-fly when loading the page with the complete content of your PhP array , either you use ajax to get back to the server without refreshing the whole page.
I am working on a project where I used ajax for asynchronous DB access.
I store the value in JavaScript variable as follows..
var content=xmlhttp.responseText;
now what I wanted is to pass this value to the php module on same page..
Please suggest me..its urgent
You'll have to make a separate AJAX request to another script to achieve this. PHP is server-sided and therefore cannot directly interact with the client.
You should handle the data (which you are assigning to content) in PHP because, as the other answers here tell you, PHP is server-side and JavaScript is on the client. If you are getting this data from a page you control, instead of var content = xhr.responseText; just modify the data BEFORE you send it. For example, if you are making an AJAX call to a process.php file on your server to get the data you are otherwise assigning to content in JavaScript, be sure to handle the data in process.php PRIOR to echo()'ing the data (which you are then storing inside content on the client):
In process.php:
// below is the normal server script which you are storing in content on the client
// echo $result;
// instead, we are going to operate on the data first:
return doSomething($result);
Then on the client:
var newContent = xhr.responseText;
And the newContent variable will contain the data you previously wished to modify with PHP. If you DO NOT have control of the server script which you are calling with AJAX, then as mentioned here already, you will need to send a SECOND AJAX call to the server with your PHP, and use $_GET or $_POST to retrieve that content data and then play with it there.
Am unclear about your need to pass value from javascript to php.
But I can give you,
A non-recommended but working approach towards your problem:
You said, you are making an Ajax call at first. While processing the corresponding server side php function, Store the response value (value of xmlhttp.responseText) into a $_SESSION variable. Finally Reload the page (using location.reload()) inside the ajax response handler function.
And a recommended approach towards your problem:
You might have added some if-else control-flow structures in the php code and expecting to execute them after getting the ajax response value (sadly you cannot do that). So if you do have some logic like that, then convert those if-else conditions to corresponding Javascript code. May be a javascript function and call that function by passing the ajax response value to it. This new function will use your ajax response value and make changes in some parts of your webpage by applying necessary logic.
I want the value of JavaScript variable which i could access using PHP.
I am using the code below but it doesn't return value of that variable in PHP.
// set global variable in javascript
profile_viewer_uid = 1;
// php code
$profile_viewer_uid=$_POST['profile_viewer_uid'];
this gives me the following error :-
A PHP Error was encountered
Severity: Notice
Message: Undefined index: profile_viewer_uid
Another php code i used which give empty value
$profile_viewer_uid = "<script language=javascript>document.write(profile_viewer_uid);</script>
When I echo it shows nothing.
Add a cookie with the javascript variable you want to access.
document.cookie="profile_viewer_uid=1";
Then acces it in php via
$profile_viewer_uid = $_COOKIE['profile_viewer_uid'];
You will need to use JS to send the URL back with a variable in it such as:
http://www.site.com/index.php?uid=1
by using something like this in JS:
window.location.href=”index.php?uid=1";
Then in the PHP code use $_GET:
$somevar = $_GET["uid"]; //puts the uid varialbe into $somevar
Here is the Working example: Get javascript variable value on the same page.
<script>
var p1 = "success";
</script>
<?php
echo "<script>document.writeln(p1);</script>";
?>
You might want to start by learning what Javascript and php are. Javascript is a client side script language running in the browser of the machine of the client connected to the webserver on which php runs. These languages can not communicate directly.
Depending on your goal you'll need to issue an AJAX get or post request to the server and return a json/xml/html/whatever response you need and inject the result back in the DOM structure of the site. I suggest Jquery, BackboneJS or any other JS framework for this. See the Jquery documentation for examples.
If you have to pass php data to JS on the same site you can echo the data as JS and turn your php data using json_encode() into JS.
<script type="text/javascript>
var foo = <?php echo json_encode($somePhpVar); ?>
</script>
If you want to use a js variable in a php script you MUST pass it within a HTTP request.
There are basically two ways:
Submitting or reloading the page (as per Chris answer).
Using AJAX, which is made exactly for communicating between a web page (js) and the server(php) without reloading/changing the page.
A basic example can be:
var profile_viewer_uid = 1;
$.ajax({
url: "serverScript.php",
method: "POST",
data: { "profile_viewer_uid": profile_viewer_uid }
})
And in the serverScript.php file, you can do:
$profile_viewer_uid = $_POST['profile_viewer_uid'];
echo($profile_viewer_uid);
// prints 1
Note: in this example I used jQuery AJAX, which is quicker to implement. You can do it in pure js as well.
PHP runs on the server. It outputs some text. Then it stops running.
The text is sent to the client (a browser). The browser then interprets the text as HTML and JavaScript.
If you want to get data from JavaScript to PHP then you need to make a new HTTP request and run a new (or the same) PHP script.
You can make an HTTP request from JavaScript by using a form or Ajax.
These are two different languages, that run at different time - you cannot interact with them like that.
PHP is executed on the server while the page loads. Once loaded, the JavaScript will execute on the clients machine in the browser.
In your html form make a hidden field
<input type="hidden" id="scanCode" name="SCANCODE"></input>
Then in your javascript update the field value by adding;
document.getElementById("scanCode").setAttribute('value', scanCode);
This could be a little tricky thing but the secure way is to set a javascript cookie, then picking it up by php cookie variable.Then Assign this php variable to an php session that will hold the data more securely than cookie.Then delete the cookie using javascript and redirect the page to itself.
Given that you have added an php command to catch the variable, you will get it.
You need to add this value to the form data that is submitted to the server. You can use
<input type="hidden" value="1" name="profile_viewer_uid" id="profile_viewer_uid">
inside your form tag.
Another question by a newbie. I have a php variable that queries the database for a value. It is stored in the variable $publish and its value will change (in the database) when a user clicks on a hyperlink.
if ($publish == '') {
Link to publish.html
} else {
Link to edit.html
}
What is happening in the background is i am querying a database table for some data that i stored in the $publish variable. If the $publish is empty, it will add a link for publish.html in a popup. The popup will process a form and will add the data to the database and which means that the $publish is no more empty. What i would like to achieve is that as soon as the form is processed in the popup and a data has been added to the database, the link should change to edit.html. This can happen when the page will re-query the database but it should happen without page refresh.
How can it be donw using javascript, jquery or ajax?? Please assist.
Javascript by itself cannot be used to deal with database. That is done using php (Or the server side language of your choice). Ajax is used to send a request to your php script using javascript which will in turn communicate with the db. And it doesn't require a page refresh.
So what you are trying to do can be easily achieved using ajax. Since you mentioned jquery, you can check out the $.ajax or $.post methods in jquery which make the process even more simple.
You need to process the form using ajax. The ajax request is sent to a php script which will make the necessary changes in the database and send the new link (link to edit.html) in the response. Upon getting the response, just replace the current anchor element with the new one ..
for eg..
$.post(url, formdataobject , function (resp) {
$("a.youra").text('edit').attr('href', resp);
});
url - where the php script is located
formdataobject - a javascript object that will have the form data as key value pairs
the third parameter is an anonymous function also known as callback function since it will be invoked only when the response is received from the server. This is because ajax requests are asynchronous.
Inside the callback function, jquery is used to change the text inside the anchor element to edit and the href attribute is changed to value that came in the response.
$.post means we are using the post method. so the parameters can be accessed as elements of $_POST array in php.
After updating the db, you can simply echo out the new link and it will be received in the response.
Also, there are other formats in which you can get the response for eg. xml, json.
I'll try to leave the technical jargon aside and give a more generic response since I think you might be confused with client-side and server-side scripting.
Think of javascript as a language that can only instruct your WEB BROWSER how to act. Javascript executes after the server has already finished processing your web page.
PHP on the other hand runs on your web server and has the ability to communicate with your database. If you want to get information from your database using javascript, you'll need to have javascript ask PHP to query the database through an AJAX call to a PHP script.
For example, you could have javascript call a script like:
http://www.myserver.com/ajax_function.php?do=queryTheDatabase
In summary: Javascript can't connect to the database but it can ask PHP to do so. I hope that helps.
Let me try, you want to change the link in a page from a pop-up that handles a form processing. Try to give your link a container:
<div id="publish_link">Publish</div>
As for the form submission use Ajax to submit data to the server to do an update and get a response back to change the link to edit or something:
$.post("submit.php", { some_field: "some_value"}, function(response) {
if(response.isPublished)
$('#publish_link', window.opener.document).html('Edit');
});
Basically your publish link is contained in a div with an ID publish_link so you change its content later after data processing without reloading the page. In the pop-up where you would do the form processing it is done using jQuery Ajax POST method to submit the data. Your script then accepts that data, update the database and if successful returns a response. jQuery POST function receives that response and there's a check there if isPublished is true, get the pop-up's opener window (your main window) and update the link to Edit. Just an idea, may not be the best out there.
It cannot be made with javascript, jquery or ajax. only server side script can query a database. with ajax request you can get the script output. ajax requests can be sent either with pure javascript or jquery.
Well, i think i understand your quaestion, but you have to get a starting point, try to understand this:
try to understand what are client variables and server variables.
javascript does not comunicate with database.
you can use javascript to retrieve data to a specific "Object variable".
Using ajax methods of jquery you can post that data do other page, that will execute the
proper actions
you can ;)
at first you must create php file to query database and return something like true or flase and then with file url check the function and get answer
function find_published(folder_id) {
var aj_url = "{{server_path}}/ajax/url"
var list;
$.getJSON(aj_url+"?callback=?&",
function(data) {
//here is your data... true false ... do every thing you want
}
);
};
this app for node.js does mysql queries https://github.com/felixge/node-mysql
You need to use AJAX for this, like .post() or .get() or JSON.