オブジェクトの順番をイントラクティブに操作させてくえるjQuery UIに含まれるSortableの紹介。
Sortableのページ
https://api.jqueryui.com/sortable/
APIの詳細
https://api.jqueryui.com/sortable/
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>jQuery UI Sortable - Default functionality</title>
<link rel="stylesheet" href="//code.jquery.com/ui/1.12.1/themes/base/jquery-ui.css">
<link rel="stylesheet" href="/resources/demos/style.css">
<style>
#sortable { list-style-type: none; margin: 0; padding: 0; width: 60%; }
#sortable li { margin: 0 3px 3px 3px; padding: 0.4em; padding-left: 1.5em; font-size: 1.4em; height: 18px; }
#sortable li span { position: absolute; margin-left: -1.3em; }
</style>
<script src="https://code.jquery.com/jquery-1.12.4.js"></script>
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script>
<script>
$( function() {
$( "#sortable" ).sortable();
$( "#sortable" ).disableSelection();
} );
</script>
</head>
<body>
<ul id="sortable">
<li class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Item 1</li>
<li class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Item 2</li>
<li class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Item 3</li>
<li class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Item 4</li>
<li class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Item 5</li>
<li class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Item 6</li>
<li class="ui-state-default"><span class="ui-icon ui-icon-arrowthick-2-n-s"></span>Item 7</li>
</ul>
</body>
</html>
順番を変更したら、新しいポジションを知りたい。そんな時は。
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.js"></script>
<script>
$(function () {
$("#sortable").sortable({
start: function (event, ui) {
ui.item.startPos = ui.item.index();
},
stop: function (event, ui) {
alert("Moved from " + ui.item.startPos + " to " + ui.item.index());
}
});
$("#sortable").disableSelection();
});
</script>