Update equation builder

assets/js/admin/equationbuilder.js

@@ -0,0 +1,37 @@
+jQuery(document).ready(function($){
+	$("#title").keyup(function() {
+		val = $(this).val();
+		if ( val == '' ) val = 'f(x)';
+		$(".sp-equation-variable").text( val + ' =' );
+	});
+
+    $(".sp-equation-parts .button").draggable({
+      appendTo: "body",
+      helper: "clone",
+      cursor: "move",
+      distance: 10,
+      containment: "#sp_equationdiv",
+    }).click(function() {
+    	$("<label class='button'></label>").text( $(this).text() ).append("<span class='remove'>&times;</span><input name='sp_equation[]' type='hidden' value='" + $(this).data("variable") + "'>").appendTo( $(".sp-equation-formula") );
+    });
+
+    $(".sp-equation").droppable({
+      activeClass: "ui-state-active",
+      hoverClass: "ui-state-hover",
+      accept: ".button:not(.ui-sortable-helper)",
+      drop: function( event, ui ) {
+        $("<label class='button'></label>").text( ui.draggable.text() ).append("<span class='remove'>&times;</span><input name='sp_equation[]' type='hidden' value='" + ui.draggable.data("variable") + "'>").appendTo( $(".sp-equation-formula") );
+      }
+    }).sortable({
+      items: ".button",
+      tolerance: "pointer",
+      containment: "#sp_equationdiv",
+      sort: function() {
+        $( this ).removeClass( "ui-state-active" );
+      }
+    });
+
+    $(".sp-equation-formula").on("click", ".button .remove", function() {
+    	$(this).closest(".button").remove();
+    });
+});