How To Pass PHP Variable To This Javascript Function?

Question

Let's say I have this PHP variables :

$SelectedCountry = "USA";
$SelectedState = "Texas";

on the other hand, I have this javascript function to display all available countries and states :

function print_country(country_id){
    // given the id of the <select> tag as function argument, it inserts <option> tags
    var option_str = document.getElementById(country_id);
    option_str.length=0;
    option_str.options[0] = new Option('Where do you live now?','');
    option_str.selectedIndex = 0;
    for (var i=0; i<country_arr.length; i++) {
        option_str.options[option_str.length] = new Option(country_arr[i],country_arr[i]);
    }
}

function print_state(state_id, state_index){
    var option_str = document.getElementById(state_id);
    option_str.length=0;    // Fixed by Julian Woods
    option_str.options[0] = new Option('Select state','');
    option_str.selectedIndex = 0;
    var state_arr = s_a[state_index].split("|");
    for (var i=0; i<state_arr.length; i++) {
        option_str.options[option_str.length] = new Option(state_arr[i],state_arr[i]);
    }
}

my question is... how to make 'USA' and 'Texas' becomes selected <option> which generated by those two javascript functions? thanks.

NOTE #1 : you can see the complete code of javascript here : http://sourceforge.net/projects/countries/files/

NOTE #2 : those function called by adding this line on my PHP :

<script type="text/javascript" src="scripts/countries.js"></script>
<script language="javascript">print_country("country");</script>

so basically I need your help how to pass that PHP variables so that it can be 'received' by javascript function INSIDE that countries.js file.

user428517 · Accepted Answer · 2012-11-15 15:10:33Z

1

One way is to just echo out some JavaScript statements:

<script>
<?php
    echo "
          var SelectedCountry = '$SelectedCountry';
          var SelectedState = '$SelectedState';
    ";
?>
</script>

Then just use them in your loops to check if the option needs to be selected or not.

If you're going to be doing a lot of this sort of thing, though, embedding PHP into JavaScript isn't really the best approach. Read up on AJAX and PHP's json_encode() function.

answered Nov 15, 2012 at 15:10

user428517

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Comments

Alex Rashkov · Accepted Answer · 2012-11-15 15:15:23Z

1

There are two answers:

1 Use AJAX cal and pass back JSON

$.ajax({
    url: '/myScript.php',
    success: function(data) {
        //Do something
    }
});

myScript.php

return json_encode($myVar);

2 Embed PHP into the JavaScript

<script>
    var myPHPVariable = <?php echo $myVar; ?>
</script>

edited Nov 15, 2012 at 15:15

answered Nov 15, 2012 at 15:09

Alex Rashkov

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3 Comments

Saint Robson Over a year ago

bro, I'm interesting with your second answer. because I don't do AJAX or JSON. but, those javascript function is not mine. I have no idea how to modify that javascript so it can recognize PHP variables and display a selected country as expected. I really appreciate if you can give me example of javascript modification. thanks bro.

Alex Rashkov Over a year ago

So to be able to embed the PHP variable your javascript should be in a PHP file for example in index.php wrap it with <script language="javascript">//Your code here</script> and than use the PHP vars inside.

Saint Robson Over a year ago

bro, what I mean is this... that two javascript functions : function print_country(country_id) and function print_state(state_id, state_index) are functions to generate <option> right? What I don't know is how to modify that javascript so that it can generate ONE <option selected>. that's all..

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