Access a JavaScript variable from PHP

2018-12-31 14:36发布

站内问答 / PHP
969 8 4

I need to access a JavaScript variable with PHP. Here's a stripped-down version of the code I'm currently trying, which isn't working:

<script type="text/javascript" charset="utf-8">
    var test = "tester";
</script>

<?php
    echo $_GET['test'];
?>

I'm a completely new to both JavaScript and PHP, so I would really appreciate any advice.

UPDATE: OK, I guess I simplified that too much. What I'm trying to do is create a form that will update a Twitter status when submitted. I've got the form working OK, but I want to also add geolocation data. Since I'm using Javascript (specifically, the Google Geolocation API) to get the location, how do I access that information with PHP when I'm submitting the form?

8条回答
冷夜・残月
2楼-- · 2018-12-31 15:02

JS ist browser-based, PHP is server-based. You have to generate some browser-based request/signal to get the data from the JS into the PHP. Take a look into Ajax.

查看更多
0人赞 添加讨论(0) 举报
妖精总统
3楼-- · 2018-12-31 15:06

Well the problem with the GET is that the user is able to change the value by himself if he has some knowledges. I wrote this so that PHP is able to retrive the timezone from Javascript:

// -- index.php

<?php
  if (!isset($_COOKIE['timezone'])) {
?>
<html>
<script language="javascript">  
  var d = new Date(); 
  var timezoneOffset = d.getTimezoneOffset() / 60;
  // the cookie expired in 3 hours
  d.setTime(d.getTime()+(3*60*60*1000));
  var expires = "; expires="+d.toGMTString();
  document.cookie = "timezone=" +  timezoneOffset + expires + "; path=/";
  document.location.href="index.php"
</script>
</html>
<?php
} else {
  ?>

  <html>
  <head>
  <body>

  <?php 
  if(isset($_COOKIE['timezone'])){ 
    dump_var($_COOKIE['timezone']); 
  } 
}
?>
查看更多
0人赞 添加讨论(0) 举报
不流泪的眼
4楼-- · 2018-12-31 15:07

I'm looking at this and thinking, if you can only get variables into php in a form, why not just make a form and put a hidden input in the thing so it doesn't show on screen, and then put the value from your javascript into the hidden input and POST that into the php? It would sure be a lot less hassle than some of this other stuff right?

查看更多
0人赞 添加讨论(0) 举报
几人难应
5楼-- · 2018-12-31 15:09

try adding this to your js function: 

    var outputvar = document.getElementById("your_div_id_inside_html_form");
    outputvar.innerHTML='<input id=id_to_send_to_php value='+your_js_var+'>';

Later in html:

    <div id="id_you_choosed_for_outputvar"></div>

this div will contain the js var to be passed through a form to another js function or to php, remember to place it inside your html form!. This solution is working fine for me.

In your specific geolocation case you can try adding the following to function showPosition(position):

    var outputlon = document.getElementById("lon1");
    outputlon.innerHTML = '<input id=lon value='+lon+'>';
    var outputlat = document.getElementById("lat1");
    outputlat.innerHTML = '<input id=lat value='+lat+'>';

later add these div to your html form:

<div id=lat1></div>
<div id=lon1></div>

In these div you'll get latitude and longitude as input values for your php form, you would better hide them using css (show only the marker on a map if used) in order to avoid users to change them before to submit, and set your database to accept float values with lenght 10,7.

Hope this will help.

查看更多
0人赞 添加讨论(0) 举报
裙下三千臣
6楼-- · 2018-12-31 15:12

_GET accesses query string variables, test is not a querystring variable (PHP does not process the JS in any way). You need to rethink. You could make a php variable $test, and do something like:

<?php
$test = "tester";
?>
<script type="text/javascript" charset="utf-8">
    var test = "<?php echo $test?>";
</script>

<?php
    echo $test;
?>

Of course, I don't know why you want this, so I'm not sure the best solution.

EDIT: As others have noted, if the JavaScript variable is really generated on the client, you will need AJAX or a form to send it to the server.

查看更多
0人赞 添加讨论(0) 举报
美炸的是我
7楼-- · 2018-12-31 15:13

The short answer is you can't.

I don't know any PHP syntax, but what I can tell you is that PHP is executed on the server and JavaScript is executed on the client (on the browser).

You're doing a $_GET, which is used to retrieve form values:

The built-in $_GET function is used to collect values in a form with method="get".

In other words, if on your page you had:

<form method="get" action="blah.php">
    <input name="test"></input>
</form>

Your $_GET call would retrieve the value in that input field.

So how to retrieve a value from JavaScript?

Well, you could stick the javascript value in a hidden form field...

<script type="text/javascript" charset="utf-8">
    var test = "tester";
    // find the 'test' input element and set its value to the above variable
    document.getElementByID("test").value = test;
</script>

... elsewhere on your page ...

<form method="get" action="blah.php">
    <input id="test" name="test" visibility="hidden"></input>
    <input type="submit" value="Click me!"></input>
</form>

Then, when the user clicks your submit button, he/she will be issuing a "GET" request to blah.php, sending along the value in 'test'.

查看更多
0人赞 添加讨论(0) 举报
1 2 下一页
登录 后发表回答
相关问题
查看全部
相关文章
查看全部
收藏的人(4)