Get variable value from the outside of javascript function [duplicate]

Question

Unable to get the correct value from the variable in side the function.

Here is my code and always i am getting id as "two", i need the correct value that i passed to change function.

<script type="text/javascript">
<?php
   $val='';
   global $val;
?>


function change(val){
  <?php //global $val;?>
      if (val=='one') {
         <?php $val='one';?>
      }
      if (val=='two') {
           <?php $val='two';?>
      }
}
</script>
<input type="button" onclick="change('one');" value="Change">

<div id="<?php echo $val;?>">

You should post the rendered html code. Such a mix of php/javascript is almost never a good idea. — Yoshi
– Yoshi, Commented Apr 2, 2014 at 8:58
It is looks like you try to mix using of client & server side code. This is really bad idea regardless of your goals. — jslayer
– jslayer, Commented Apr 2, 2014 at 8:59
Many apps are a mix of client & server code. But they are written by engineers who know what is happening on the server and client. — Paul
– Paul, Commented Apr 2, 2014 at 9:00

nedt · Accepted Answer · 2014-04-02 09:02:52Z

1

Well the PHP code executed independent of your javascript code, which is only executed afterwards on the client side. So what your script does is executing this in PHP:

<?php
global $val;
$val='one';
$val='two';
?>
<!-- ... -->
<div id="<?php echo $val;?>">

and this is the code on the client side:

<script type="text/javascript">
    function change(val){

      if (val=='one') {
      }
      if (val=='two') {
      }
     }
</script>
<input type="button" onclick="change('one');" value="Change">

So if you want to change an element you'll have to do it in Javascript:

<script type="text/javascript">    
    function change(val){
      var el = document.getElementsByTagName('div')[0];

      if (val=='one') {
        el.id = 'one';
      }
      if (val=='two') {
        el.id = 'two';
      }
     }

</script>
<input type="button" onclick="change('one');" value="Change">

<div id="">

answered Apr 2, 2014 at 9:02

nedt

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3 Comments

Paul Over a year ago

Is "" a valid HTML id? Would it be better to make it one or the other, and then use document.getElementById ?

nedt Over a year ago

I've kept my changes small and left the id uninitialised, because it is in the original question. But yes it's invalid. And yes I'd also have a unique selector for the changed element (maybe a class). I also don't see how changing the id could be useful ...

user3356107 Over a year ago

Thanks a lot, it helps and working.

Rohan Kumar · Accepted Answer · 2014-04-02 09:14:23Z

1

You are mixing server-side-script and client-side-script try it in javascript like,

SCRIPT

<script type="text/javascript">
    var val='one'; // global value
    function change(){
        if (val=='one') {
           // your code for one
           val='two'; // change the value of val to two
        }
        else if (val=='two') {
            // your code for two
            val='one'; // again change val value
        }
        document.getElementsByClassName('changed_value')[0].id=val;
        document.getElementById(val).innerHTML=val;
    }
</script>

HTML

<input type="button" onclick="change();" value="Change">
<div class="changed_value"></div>

Live Demo

edited Apr 2, 2014 at 9:14

answered Apr 2, 2014 at 9:00

Rohan Kumar

40.7k11 gold badges81 silver badges111 bronze badges

3 Comments

user3356107 Over a year ago

Thanks for the quick reply, i need to print the "val" value in the html code like <div id="{val}"></div>

Rohan Kumar Over a year ago

Try my updated answer and demo

user3356107 Over a year ago

I have done my task with the above suggestion's thanks

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