限制元素追加Javascript的数量

Question

I have a simple bit of code to append additional select fields to a form, with the idea that the user can add more fields as required. However, I want to be able to define a maximum number of input elements that can be appended. My current code is:

<script type="text/javascript">
var count = 0;
$(function(){
    $('p#add_field').click(function(){
        count += 1;
        $('#container2').append(
                '<strong>Golf Course ' + count + '</strong>&nbsp&nbsp&nbsp' 
                +'<select id="field_' + count + '" name="fields[]">' + "<?php foreach ( $courses as $course ) { $name = $course->coursename; ?>"+"<?php echo '<option value=\''.htmlspecialchars($name).'\'>'.$name.'</option>'; ?>"+"<?php } ?>"+'</select><br />')

    });
});
</script>

Any help would be much appreciated.

Answer 1

<script type="text/javascript">
var count = 0;
var max = 5;
$(function(){
    $('p#add_field').click(function(){
        count += 1;
        if(count >= max)
            return;

        $('#container2').append(
                '<strong>Golf Course ' + count + '</strong>&nbsp&nbsp&nbsp' 
                +'<select id="field_' + count + '" name="fields[]">' + "<?php foreach ( $courses as $course ) { $name = $course->coursename; ?>"+"<?php echo '<option value=\''.htmlspecialchars($name).'\'>'.$name.'</option>'; ?>"+"<?php } ?>"+'</select><br />')

    });
});
</script>

Still, your code is quite unmaintainable - separate PHP from JS.

EDIT: consider this solution as well:

// this way you provide a JSON serialization of your server data
<script type="application/json" id="select-data">
<?php echo json_encode($courses); ?>
</script>

// this is pure js: doesn't care where the data comes from
<script type="text/javascript">

$(function(){

    // we parse the JSON string, and get a Javascript array
    var selectData = $.parseJSON( $("#select-data").text() );
    var count = 0;
    var max = 5; // pick the number you want here

    // we create a new select, based on the count parameter
    function makeSelect(count){

        var $select = $('<select>', { id : 'field_' + count, name : "fields[]" });

        $.each(selectData, function(){

            $select.append(
                $('<option>', { value : this.name, text : this.name })
            )

        })

        return $select; 

    }

    $('p#add_field').click(function(){
        count += 1;
        if(count >= max)
            return;

        $('#container2').append($('<strong>', { text : "Golf Course " + count }));
        $('#container2').append(makeSelect(count));

    });
});

</script>

Answer 2

try this

<script type="text/javascript">
    var count = 0;
    var limit = 5;
    $(function () {
        $('p#add_field').click(function () {
            count += 1;
            if ($('#container2 select').length <= limit) {
                $('#container2').append(
            '<strong>Golf Course ' + count + '</strong>&nbsp&nbsp&nbsp'
            + '<select id="field_' + count + '" name="fields[]">' + "<?php foreach ( $courses as $course ) { $name = $course->coursename; ?>" + "<?php echo '<option value=\''.htmlspecialchars($name).'\'>'.$name.'</option>'; ?>" + "<?php } ?>" + '</select><br />')
            }
            else {
                alert('Limit Exceed');
            }
        });
    });
</script>