What are some common search terms or resources for implementing multi-level select options in PHP forms using JavaScript or jQuery?

When implementing multi-level select options in PHP forms using JavaScript or jQuery, common search terms include "dynamic dropdowns," "cascading dropdowns," or "dependent dropdowns." One way to achieve this is by using AJAX to fetch data from the server based on the selected options in the dropdowns. This allows for dynamically updating the options in subsequent dropdowns based on the user's selections. 

<?php
// PHP code to fetch data for the dropdowns
$first_level_options = array("Option 1", "Option 2", "Option 3");

echo '<select id="first_level">';
foreach($first_level_options as $option) {
    echo '<option value="'.$option.'">'.$option.'</option>';
}
echo '</select>';

echo '<select id="second_level"></select>';

echo '<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>';
echo '<script>
$(document).ready(function(){
    $("#first_level").change(function(){
        var selectedOption = $(this).val();
        
        $.ajax({
            url: "get_second_level_options.php",
            type: "POST",
            data: {first_level_option: selectedOption},
            success: function(data){
                $("#second_level").html(data);
            }
        });
    });
});
</script>';
?>

Keywords

PHP JavaScript jQuery multi-level select options forms

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