diff --git a/lib/helpers/document/applyVirtuals.js b/lib/helpers/document/applyVirtuals.js
index e3869440b9..43cb0a047c 100644
--- a/lib/helpers/document/applyVirtuals.js
+++ b/lib/helpers/document/applyVirtuals.js
@@ -4,7 +4,16 @@ const mpath = require('mpath');
 
 module.exports = applyVirtuals;
 
-function applyVirtuals(schema, doc, virtuals, parent) {
+/**
+ * Apply a given schema's virtuals to a given POJO
+ *
+ * @param {Schema} schema
+ * @param {Object} doc
+ * @param {Array<string>} [virtuals] optional whitelist of virtuals to apply
+ * @returns
+ */
+
+function applyVirtuals(schema, doc, virtuals) {
   if (doc == null) {
     return doc;
   }
@@ -15,9 +24,7 @@ function applyVirtuals(schema, doc, virtuals, parent) {
   if (Array.isArray(virtuals)) {
     virtualsForChildren = [];
     toApply = [];
-    const len = virtuals.length;
-    for (let i = 0; i < len; ++i) {
-      const virtual = virtuals[i];
+    for (const virtual of virtuals) {
       if (virtual.length === 1) {
         toApply.push(virtual[0]);
       } else {
@@ -26,28 +33,23 @@ function applyVirtuals(schema, doc, virtuals, parent) {
     }
   }
 
-  applyVirtualsToChildren(this, schema, doc, virtualsForChildren, parent);
-  return applyVirtualsToDocs(schema, doc, toApply);
+  applyVirtualsToChildren(schema, doc, virtualsForChildren);
+  return applyVirtualsToDoc(schema, doc, toApply);
 }
 
-function applyVirtualsToDocs(schema, res, toApply) {
-  if (Array.isArray(res)) {
-    const len = res.length;
-    for (let i = 0; i < len; ++i) {
-      applyVirtualsToDoc(schema, res[i], toApply);
-    }
-    return res;
-  } else {
-    return applyVirtualsToDoc(schema, res, toApply);
-  }
-}
+/**
+ * Apply virtuals to any subdocuments
+ *
+ * @param {Schema} schema subdocument schema
+ * @param {Object} res subdocument
+ * @param {Array<String>} [virtuals] optional whitelist of virtuals to apply
+ */
 
-function applyVirtualsToChildren(doc, schema, res, virtuals, parent) {
-  const len = schema.childSchemas.length;
+function applyVirtualsToChildren(schema, res, virtuals) {
   let attachedVirtuals = false;
-  for (let i = 0; i < len; ++i) {
-    const _path = schema.childSchemas[i].model.path;
-    const _schema = schema.childSchemas[i].schema;
+  for (const childSchema of schema.childSchemas) {
+    const _path = childSchema.model.path;
+    const _schema = childSchema.schema;
     if (!_path) {
       continue;
     }
@@ -59,9 +61,7 @@ function applyVirtualsToChildren(doc, schema, res, virtuals, parent) {
     let virtualsForChild = null;
     if (Array.isArray(virtuals)) {
       virtualsForChild = [];
-      const len = virtuals.length;
-      for (let i = 0; i < len; ++i) {
-        const virtual = virtuals[i];
+      for (const virtual of virtuals) {
         if (virtual[0] == _path) {
           virtualsForChild.push(virtual.slice(1));
         }
@@ -72,22 +72,31 @@ function applyVirtualsToChildren(doc, schema, res, virtuals, parent) {
       }
     }
 
-    applyVirtuals.call(doc, _schema, _doc, virtualsForChild, res);
+    applyVirtuals(_schema, _doc, virtualsForChild);
     attachedVirtuals = true;
   }
 
   if (virtuals && virtuals.length && !attachedVirtuals) {
-    applyVirtualsToDoc(schema, res, virtuals, parent);
+    applyVirtualsToDoc(schema, res, virtuals);
   }
 }
 
+/**
+ * Apply virtuals to a given document. Does not apply virtuals to subdocuments: use `applyVirtualsToChildren` instead
+ *
+ * @param {Schema} schema
+ * @param {Object} doc
+ * @param {Array<String>} [virtuals] optional whitelist of virtuals to apply
+ * @returns
+ */
+
 function applyVirtualsToDoc(schema, doc, virtuals) {
   if (doc == null || typeof doc !== 'object') {
     return;
   }
   if (Array.isArray(doc)) {
-    for (let i = 0; i < doc.length; ++i) {
-      applyVirtualsToDoc(schema, doc[i], virtuals);
+    for (const el of doc) {
+      applyVirtualsToDoc(schema, el, virtuals);
     }
     return;
   }
@@ -107,25 +116,25 @@ function applyVirtualsToDoc(schema, doc, virtuals) {
   if (virtuals == null) {
     virtuals = Object.keys(schema.virtuals);
   }
-  const numVirtuals = virtuals.length;
-  for (let i = 0; i < numVirtuals; ++i) {
-    const virtual = virtuals[i];
+  for (const virtual of virtuals) {
     if (schema.virtuals[virtual] == null) {
       continue;
     }
     const virtualType = schema.virtuals[virtual];
     const sp = Array.isArray(virtual)
-      ? virtual :
-      virtual.indexOf('.') === -1
+      ? virtual
+      : virtual.indexOf('.') === -1
         ? [virtual]
         : virtual.split('.');
     let cur = doc;
-    for (let j = 0; j < sp.length - 1; ++j) {
-      cur[sp[j]] = sp[j] in cur ? cur[sp[j]] : {};
-      cur = cur[sp[j]];
+    for (let i = 0; i < sp.length - 1; ++i) {
+      cur[sp[i]] = sp[i] in cur ? cur[sp[i]] : {};
+      cur = cur[sp[i]];
     }
     let val = virtualType.applyGetters(cur[sp[sp.length - 1]], doc);
-    if (isPopulateVirtual(virtualType) && val === undefined) {
+    const isPopulateVirtual =
+      virtualType.options && (virtualType.options.ref || virtualType.options.refPath);
+    if (isPopulateVirtual && val === undefined) {
       if (virtualType.options.justOne) {
         val = null;
       } else {
@@ -135,7 +144,3 @@ function applyVirtualsToDoc(schema, doc, virtuals) {
     cur[sp[sp.length - 1]] = val;
   }
 }
-
-function isPopulateVirtual(virtualType) {
-  return virtualType.options && (virtualType.options.ref || virtualType.options.refPath);
-}
diff --git a/lib/model.js b/lib/model.js
index 8978718d5b..1c361bcb49 100644
--- a/lib/model.js
+++ b/lib/model.js
@@ -3521,24 +3521,24 @@ Model.applyDefaults = function applyDefaults(doc) {
  *     obj.name; // 'John'
  *     obj.upper; // 'JOHN', Mongoose applied the return value of the virtual to the given object
  *
- * @param {Object} doc object or document to apply virtuals on
+ * @param {Object} obj object or document to apply virtuals on
  * @param {Array<string>} [virtualsToApply] optional whitelist of virtuals to apply
- * @returns {Object} doc
+ * @returns {Object} obj
  * @api public
  */
 
-Model.applyVirtuals = function applyVirtuals(doc, virtualsToApply) {
-  if (doc == null) {
-    return doc;
+Model.applyVirtuals = function applyVirtuals(obj, virtualsToApply) {
+  if (obj == null) {
+    return obj;
   }
   // Nothing to do if this is already a hydrated document - it should already have virtuals
-  if (doc.$__ != null) {
-    return doc;
+  if (obj.$__ != null) {
+    return obj;
   }
 
-  applyVirtualsHelper(this.schema, doc, virtualsToApply, null);
+  applyVirtualsHelper(this.schema, obj, virtualsToApply);
 
-  return doc;
+  return obj;
 };
 
 /**