Drag and Drop: Further testing of new feature "can reuse".

common/static/js/capa/drag_and_drop/draggables.js

@@ -63,6 +63,8 @@ define(['logme', 'update_input'], function (logme, updateInput) {
         var draggableObj, obj;
 
         draggableObj = {
+            'uniqueId': /* this.uniqueId */ this.state.getUniqueId(), // Is newly set.
+
             'originalConfigObj': this.originalConfigObj,
             'stateDraggablesIndex': /* this.stateDraggablesIndex */ null, // Will be set.
 
@@ -379,6 +381,8 @@ define(['logme', 'update_input'], function (logme, updateInput) {
         var draggableObj;
 
         draggableObj = {
+            'uniqueId': state.getUniqueId(),
+
             'originalConfigObj': obj,
             'stateDraggablesIndex': null,
 
@@ -768,7 +772,7 @@ define(['logme', 'update_input'], function (logme, updateInput) {
             if (
                 (this.state.config.onePerTarget === true) &&
                 (target.draggableList.length === 1) &&
-                (target.draggableList[0].id !== this.id)
+                (target.draggableList[0].uniqueId !== this.uniqueId)
             ) {
                 continue;
             }

common/static/js/capa/drag_and_drop/state.js

@@ -26,9 +26,33 @@ define([], function () {
 
             'targets': [],
 
-            'updateArrowOpacity': null
+            'updateArrowOpacity': null,
+
+            'uniqueId': 0,
+            'salt': makeSalt(),
+
+            'getUniqueId': getUniqueId
         };
     }
+
+    function getUniqueId() {
+        this.uniqueId += 1;
+
+        return this.salt + '_' + this.uniqueId.toFixed(0);
+    }
+
+    function makeSalt() {
+        var text, possible, i;
+
+        text = '';
+        possible = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
+
+        for(i = 0; i < 5; i += 1) {
+            text += possible.charAt(Math.floor(Math.random() * possible.length));
+        }
+
+        return text;
+    }
 });
 
 // End of wrapper for RequireJS. As you can see, we are passing

common/static/js/capa/drag_and_drop/targets.js

@@ -15,7 +15,7 @@ define(['logme'], function (logme) {
                 c1 += 1;
             }
         }(0));
-    } // function Targets(state) {
+    }
 
     function processTarget(state, obj) {
         var targetEl, borderCss, numTextEl, targetObj;
@@ -36,7 +36,6 @@ define(['logme'], function (logme) {
                     'left: ' + obj.x + 'px; ' +
                     borderCss +
                 '" ' +
-                'data-target-id="' + obj.id + '" ' +
             '></div>'
         );
         targetEl.appendTo(state.baseImageEl.parent());