Javascript not able to print large string - javascript

I am entirely new to JavaScript and the only reason I need it now is to update a picture on a PHP page. The picture is in Base64. This is the code I currently have:
if($data != null){
$data = "data:image/jpeg;base64, " . $data;
?>
<script type="text/javascript">
var myvar = "<?php echo ($data); ?>";
document.write("test" + myvar);
</script>
This simply does not output anything.
However, if I try something like this:
if($data != null){
$data = "data:image/jpeg;base64, " . $data;
?>
<script type="text/javascript">
document.write("test" + "<?php echo strlen($data); ?>");
</script>
it does work and outputs a number somewhere between 10.000 and 20.000. I read on the internet that there is not really a max variable size in JavaScript, atleast not one I am able to reach with this size.
What am I doing wrong?

Related

How can i add two variables between single quotes

I have
function delImage(posteId,imagebinId) {
$.get("<?php echo base_url('/Home/deletePostimage/') ?>");
return false;
}
i want to be like /Home/deletePostimage/posteId/imagebinId
i tried
$.get("<?php echo base_url('/Home/deletePostimage/')+posteId+"/"+imagebinId ?>");
but it divide the two numbers
like posteId=5 imagebinId =2
the results will be
/Home/deletePostimage/2,5
the params from
<a class="postimgsd" onClick="if(confirm('Are you sure you want to delete this image ?')){delImage(<?php echo $value['id'],$get_images[0]['binId']; ?>); rmItem(<?php echo $i; ?>);}else{} ; " >
With ES6, you can do this with string interpolation:
$.get(`<?php echo base_url('/Home/deletePostimage/${postId}/${imagebinId}') ?>`);
Without ES6, there is another answer that answers it, or use this:
var url = '/Home/deletePostimage/' + postId + '/' + imagebinId;
$.get("<?php echo base_url('" + url + "') ?>");
Furthermore, the code that calls this function should actually be:
<a class="postimgsd" onClick="checkDeletion()" />
<script type='text/javascript'>
function checkDeletion() {
if(confirm('Are you sure you want to delete this image ?')) {
var postId = <?php echo $value['id']; ?>;
var imagebinId = <?php echo $get_images[0]['binId']; ?>;
delImage(postId, imagebinId);
rmItem(<?php echo $i; ?>);
}
}
</script>
You need to keep in mind that PHP is processed on back-end before send the html to your user browser. That said, everything between php tags (<?php ... ?>) is rendered/processed before javascript even exists.
So if you put any JavaScript code inside your PHP code it won't work.
To make it work and be clean, do something like this:
function delImage(posteId,imagebinId) {
let url = "<?php echo base_url('/Home/deletePostimage/') ?>";
$.get(url + posteId + "," + imagebinId);
return false;
}

Get javascript variable value in php

I need to get javascript variable value in php file.
html example:
UPDATE:
$html = '
<script>
window.runParams.adminSeq="3423423423423";
window.runParams.companyId="2349093284234";
</script>';
Shout I use regex ? regex is very complex to me... any help ?
<?php
$html = '<script>
window.runParams.adminSeq="3423423423423";
window.runParams.companyId="2349093284234";
</script>';
$variables = ["adminSeq", "companyId"];
$counter = 0;
foreach($variables as $variable) {
preg_match_all('/"(.*?)"/', $html, $matches);
${"$variable"} = ($matches[1])[$counter];
$counter++;
}
echo $adminSeq; // Prints out: 3423423423423
echo $companyId; // Prints out: 2349093284234
?>
You can also use GET requests to do this. The link would look like http://localhost/?adminSeq=3423423423423&companyId=2349093284234 then get out these values in PHP with:
<?php
$adminSeq = $_GET["adminSeq"];
$companyId = $_GET["companyId"];
?>

Referencing a defined html variable in JS

My index.php page includes a config.php file, which returns an array that I have defined some variables in by using "define('var1' , 10)".
I am trying to validate my forms input, but I can't figure out how I can reference var1 from within the JS function. What is the easiest way to do this?
Just echo it to a javascript variable:
<script type="text/javascript">
var var1JS = "<?php echo $var1; ?>";
</script>
Not quite sure I am full understanding without seeing the code but, you could echo the variable from the PHP array in the JS function (as above answer).
Or Echo the entire JS query:
$y = count($PHPdata_array);
echo "function exampleFunction() {";
echo "var ArrayName = [";
for ($i = 1; $i <= $y; $i+=2) {
echo "{" . $PHPdata_array[$i] . "," . $PHPdata_array[$i-1] . "},";
}
echo "];";

How to retrieve $_SESSION value in a JavaScript/HTML

I have this working script yet when I change it to retrieve(supposedly) the value inside $_SESSION["username"], it doesn't retrieve anything. The whole page is saved as .php as I am using some codes that uses PHP.
Code:
echo "<script type=text/javascript>";
echo "var hidden = false;";
echo "function actiondb1() {";
echo "if(!hidden) {";
echo "document.getElementById(\'clickdb1\').style.visibility = \'hidden\';";
echo "document.getElementById(\'db1\').style.visibility = \'visible\';";
echo "document.getElementById(\'db1\').disabled = false;";
echo "document.getElementById(\'db1\').value =".$_SESSION["username"];.";";
echo "}";
echo "}";
echo "</script>";
How can I make the script to properly retrieve the data inside $_SESSION["username"];?
Observe that, for instance, if the value of $_SESSION["username"] is John, your echo will be generating this result:
document.getElementById('db1').value = John;
But John is supposed to be a string and should be wrapped in quotation marks, otherwise JavaScript will understand it as a variable name (which value will be probably undefined).
As Havenard mentioned, this line is missing Javascript single quotes to properly denote a string variable:
echo "document.getElementById(\'db1\').value ='".$_SESSION["username"];."';";
However, you really shouldn't print JS out with PHP if you can help it. Though iatboy's answer answer won't ultimately fix your bug, it is a much cleaner way of doing things.
?>
<script type=text/javascript>;
var hidden = false;
function actiondb1() {
if(!hidden) {
document.getElementById('clickdb1').style.visibility = 'hidden';
document.getElementById('db1').style.visibility = 'visible';
document.getElementById('db1').disabled = false;
document.getElementById('db1').value ='<?php echo $_SESSION["username"];?>';
}
}
</script>;
<?php
Did you start session in this page?If you didn't,use the follow code to start session.
session_start();
Then change your code to
echo "<script type=text/javascript>";
echo "var hidden = false;\n";
echo "function actiondb1() {\n";
echo "alert('".$_SESSION['username']."')\n"; //test code
echo "if(!hidden) {\n";
echo "document.getElementById('clickdb1').style.visibility = 'hidden';\n";
echo "document.getElementById('db1').style.visibility = 'visible';\n";
echo "document.getElementById('db1').disabled = false;\n";
echo "document.getElementById('db1').value ='".$_SESSION["username"]."';\n";
echo "}\n";
echo "}\n";
echo "</script>";
it will be ok.

Setting JS variable to PHP variable error

I want to use a php login name in my javascript game...
I have this at the top of my php page that runs the javascript:
<?php
$username = (isset($_GET['username']) ? ($_GET['username']) : "dude");
?>
In my javascript I have this... which doesn't alert the name at all and throws a Uncaught ReferenceError: daniel is not defined error:
var name = <?php echo $username; ?>;
alert(name);
And then I have this... which displays the name correctly at the top of the HTML:
<?php
echo "Welcome back " . $username . "...";
?>
If the name is being displayed correctly server side when the page has loaded, why can't it be alerted out from the Javascript?
Thanks
You aren't delimiting the value as a JavaScript string. It may be a string on the server, but not on the client. Do the following:
Change this:
var name = <?php echo $username; ?>;
To this:
var name = "<?php echo $username; ?>";
Enclose your php code within quotes.Try like this :
<script type="text/javascript">
var name = '<?php echo $username; ?>';
alert(name);
</script>

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