How to use AJAX to POST to PHP?
Question
As I asked here I would like to know how I could pass the data from a simple JS function to php, and log it there.
I found this answer and tried to follow it. This is my code right now (both in the same file)
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js" type="text/javascript"> </script>
</head>
<body>
<script>
function getClientScreenResolution() {
var screenResolutionW = screen.width;
var screenResolutionH = screen.height;
console.log(screenResolutionW + ' ' + screenResolutionH)
$.post("index.php", {screenResolutionW: screenResolutionW, screenResolutionH: screenResolutionH})
}
</script>
<script type="text/javascript">
getScreenResolution();
</script>
</body>
</html>
<?php
$screenResolutionW = $_POST['screenResolutionW'];
$screenResolutionH = $_POST['screenResolutionH'];
if(isset($_POST['screenResolutionW'])) {
$fh = fopen('log.txt', 'a');
fwrite($fh, 'Screen res: '."".$screenResolutionW .'x'."".$screenResolutionH
."\r\n");
fclose($fh);
}
?>
However, this does not work. I wouldn't know how to fix this, whenever I try to google this problem people use more advanced methods, that I wouldn't even know how to start with.
Edit: My PHP and HMTL are in the same file (index.php). Edit 2: Removed old code for clarity.
This results in these error messages:
Notice: Undefined index: screenResolutionW in index.php on line 153
Notice: Undefined index: screenResolutionH in index.php on line 154
4 answers
solution1
3 ACCPTED 2020-05-01 13:30:38
What you want to do with $.post is include your data like this:
$.post("index.php", {screenResolutionW: screenResolutionW, screenResolutionH: screenResolutionH})
where the first of the pair is the POST identifier (the ['screenResolutionW'] ) and the second of the pair is the variable value.
You will also want to change your POST identifiers to be quoted:
$screenResolutionW = $_POST['screenResolutionW'];
$screenResolutionH = $_POST['screenResolutionH'];
Otherwise, you will get a warning about constants. I have also corrected the spelling in these variables, to reflect what you're trying to write into your file.
fwrite($fh, 'Screen res: '."".$screenResolutionW .'x'."".$screenResolutionH ."\r\n");
EDIT
Part of the problem is that you never call the function to execute it. Here is your HTML with the additions I have suggested, plus calling the function:
EDIT TWO
Added an onload handler for the document:
<html>
<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js" type="text/javascript"> </script>
</head>
<body>
<script>
function getScreenResolution() {
var screenResolutionW = screen.width;
var screenResolutionH = screen.height;
console.log(screenResolutionW + ' ' + screenResolutionH);
$.post("index.php", {screenResolutionW: screenResolutionW, screenResolutionH: screenResolutionH})
}
</script>
</body>
<script type="text/javascript">
$(function() {
getScreenResolution();
});
</script>
</html>
OTHER NOTES
You really should separate the PHP code and place it in a different file because when you run the page as it is now you should get one line logged that has no variables when the page initially runs, then one logged line when the JavaScript fires after the page loads.
Then once separated you should not run your PHP until you test for the existence of a variable, for example:
if(isset($_POST['screenResolutionW'])) {
// your code to write to the file here
}
EDIT THREE
I placed all of the JavaScript in the same script block in the head of the file and have tested again:
<html>
<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js" type="text/javascript"> </script>
<script type="text/javascript">
$(function() {
function getScreenResolution() {
var screenResolutionW = screen.width;
var screenResolutionH = screen.height;
console.log(screenResolutionW + ' ' + screenResolutionH);
$.post("post_test.php", {screenResolutionW: screenResolutionW, screenResolutionH: screenResolutionH})
}
getScreenResolution();
});
</script>
</head>
<body>
</body>
</html>
Here you can see the variables are being posted:
solution2
1 2020-05-01 14:13:41
Adapting the others answers.
try it:
function getScreenResolution() {
"http://example.com/index.php", screenResolutionW + screenResolutionH
$.ajax({
url: '/index.php',
method: 'POST',
data: {
screenResolutionW : screen.width,
screenResolutionH : screen.height
},
success: function(data) { console.log(data); }
});
}
And in your PHP
$screenResolutionW = $_POST['screenResolutionW'];
$screenResolutionH = $_POST['screenResolutionH'];
echo $screenResolutionW . " - " . $screenResolutionH;
solution3
0 2020-05-01 13:46:01
you have to use serialize the array before doing post request.
var screenResolutionW = screen.width;
var screenResolutionH = screen.height;
var serializedArr = {
width: screenResolutionW,
height: screenResolutionH
};
$.post('/index.php', serializedArr, function(response) {
// Log the response to the console
console.log("Response: "+response);
});
In the server end, you will get values in $_POST variable.
solution4
-1 2020-05-01 14:15:52
Apart of all those mistakes you have discovered thanks to other replies, you have these: $screenResoltuionW =...
Notice you wrote "ltuion" and in the fopen command you have it correct. screenResolutionW
Same thing with $screenResoltuionH...
That's why you don't get any value in the file, because those variables doesn't exists.
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