see if item exists in a select element with jquery/PHP

This is a bizarre request but i have two select elements on my page, one for old project numbers and one for new project numbers. I am using PHP to populate the dropdowns from a mysql db. I have also set up a GET variable which will hold an incoming project number 开发者_如何学Cfrom a hyperlink people click on another page. But what i want to do is use jQuery/PHP to take that incoming project number and see if it exists in either of the dropdowns?

This is the GET code:

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

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You can assign a JavaScript variable with PHP:

<?php
/*... other php */
echo 'var projectNumber = "' . $_GET['project_no'] . '";';
/*... other php */
?>

Which renders to:

var projectNumber = "12345"; // or whatever value 'project_no' might contain

And then, in jQuery:

$('select > option:contains(' + projectNumber + ')').attr('selected',true);

This, obviously, selects the value. You could just as easily use an if statement of some sort, though. It depends on what you wanted to do with the values, if found.

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Edited to add the following selector, which is slightly more meaningful, and uses a slightly more obvious attribute equals selector, though this doesn't look at the text, which the previous example, with :contains() does:

$('select > option[value=' + projectNumber + ']').attr('selected',true);

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You would need to interate through the option nodes and compare the values.

function lookup(check, cb) {
    $('#somedropdown').find('option').each(function(index, elem) {
        if( elem.value === check ) {
            cb();
            return false;
        }
    });
}

$.ajax({
    // ...
    success: function(data) {
         lookup(data.project_name_for_instance, function() {
              // match
         });
    },
    // ...
});

---

view online demo here: http://jsfiddle.net/APXGv/

//jQuery sweetness
if($("#dropdown option[value='<?php echo $_GET['project_no']; ?>'").size()){
    alert("exists");
    //your code here...
}