how to pass php variable to javascript?

Question

I am using following code to pass PHP variables to javascript. but it is not working.

 function gto(str) {
 document.getElementById('goto').action = str;
 document.getElementById('ID').value = <?php echo "$userid" ?>;
 document.getElementById('name').value = <?php echo "$user_name" ?>;
 document.getElementById('gname').value = <?php echo "$usergname" ?>;
 document.getElementById('fmname').value = <?php echo "$userfname" ?>;
 document.getElementById('img').value = <?php echo "$userimg" ?>;
 document.getElementById('email').value = <?php echo "$useremail" ?>;
 document.getElementById('goto').submit();
 }

Following is the PHP code

<?php
 if($_POST["name"] == null)
 {
 $user_name = 'Annomyous'; 
 }
 else{
 $user_name = $_POST["name"];
 $userid= $_POST["id"];
 $usergname= $_POST["gname"];
 $userfname= $_POST["fname"];
 $userimg= $_POST["img"];
 $useremail= $_POST["email"];
 }
 echo "<p style='color : white'>$user_name";
 echo "$userid" ;
 echo "$gname";
 echo "$fname";
 echo "$img";
 echo "$email";
 echo "$user_name";
 echo "$user_name</p>";
 $user_name =htmlspecialchars($user_name);
 $user_name =str_replace("<script>","", $user_name);
 ?>
the output is a follows:
ReAlItY TuTs104598758504708047866ReAlItY TuTsReAlItY TuTs//this is php echo output.

JAVASCRIPT OUTPUT:-

 function gto(str) {
 document .getElementById('goto').action = str;
 document.getElementById('ID').value = ;
 document.getElementById('name').value = Annomyous;
 document.getElementById('gname').value = ;
 document.getElementById('fmname').value = ;
 document.getElementById('img').value = ;
 document.getElementById('email').value = ;
 document.getElementById('goto').submit();
 }

Function gto is called here:

<button class="w3-btn header-btn" onclick="gto('Contact.php');">Contact Us</button>

I can see in PHP output I am getting all variable output. but nin juavascript im getting only Annonymous why???? I need to pass post variables to contact us so i am using the form tag and javascript but this is not working Please help me! Thanks in Advance

• Devsi Odedra: you can pass php variable value javascript as var variablename = <?= $phpvariablename ?>
• CertainPerformance: You have way too many empty strings in the output - it looks like you need to fix the initial communication between the form and your endpoint first.
• Khushit Shah: @CertainPerformance w3schools.com/code/tryit.asp?filename=FQS9PAD2HFWF
• Kento Nishi: Thanks for the upvote! I can now comment!
• Kento Nishi: I already did! It had 1 negative vote so I cancelled it out.

Answer 1

values from php to js can be passed in many ways, here's one of them
try to pass the php values when calling the js function, like this:-

<button onclick="gto('Contact.php','<?php echo $userid;?>','<?php echo $username;?>');">Contact Us</button>

and then get values on js function like this:-

 function gto(str,userid,username) {
 document .getElementById('goto').action = str;
 document.getElementById('ID').value = userid;
 document.getElementById('name').value =username;
 }

that's it, now use the values in js as your wish

• Kento Nishi: hey, a relevant solution! mine was... not really the problem. oh well :P

Answer 2

Uh, found another issue. The js is in smart quotes, which won't work... "`" is invalid. use "'". Also, w3schools can't handle php in their editor, so it's no use. Example for POST requests: https://www.w3schools.com/code/tryit.asp?filename=FQSA8MJYGJ47

Hope this helps.