MDL-31315 Ask before moving away from a modified form

lib/javascript-static.js

@@ -1752,4 +1752,72 @@ M.util.load_flowplayer = function() {
         fileref.onreadystatechange = embed_function;
         document.getElementsByTagName('head')[0].appendChild(fileref);
     }
+};
+
+/**
+ * Set the form changed state to true
+ */
+M.util.set_form_changed = function() {
+    M.cfg.form_changed = 1;
+};
+
+/**
+ * Set the form submitted state to true
+ */
+M.util.set_form_submitted = function() {
+    M.cfg.form_submitted = 1;
 }
+
+/**
+ * Attempt to determine whether the form has been modified in any way and
+ * is thus 'dirty'
+ *
+ * @return Integer 1 is the form is dirty; 0 if not
+ */
+M.util.get_form_dirty_state = function() {
+    // If the form was submitted, then return a non-dirty state
+    if (M.cfg.form_submitted) {
+        return 0;
+    }
+
+    // If any fields have been marked dirty, return a dirty state
+    if (M.cfg.form_changed) {
+        return 1;
+    }
+
+    // Handle TinyMCE editor instances
+    // We can't add a listener in the initializer as the editors may not have been created by that point
+    // so we do so here instead
+    if (typeof tinyMCE != 'undefined') {
+        for (var editor in tinyMCE.editors) {
+            if (tinyMCE.editors[editor].isDirty()) {
+                return 1;
+            }
+        }
+    }
+
+    // If we reached here, then the form hasn't met any of the dirty conditions
+    return 0;
+};
+
+/**
+ * Return a suitable message if changes have been made to a form
+ */
+M.util.report_form_dirty_state = function(e) {
+    if (!M.util.get_form_dirty_state()) {
+        // the form is not dirty, so don't display any message
+        return;
+    }
+
+    // This is the error message that we'll show to browsers which support it
+    var returnValue = M.util.get_string('changesmadereallygoaway', 'moodle');
+
+    // Most browsers are happy with the returnValue being set on the event
+    // But some browsers do not consistently pass the event
+    if (e) {
+        e.returnValue = returnValue;
+    }
+
+    // But some require it to be returned instead
+    return returnValue;
+};