Optimise decamelizeKeys

package.json

@@ -25,7 +25,6 @@
     "google-auth-library": "^9.15.1",
     "google-gax": "^5.0.1",
     "long": "^4.0.0",
-    "map-obj": "^4.0.0",
     "stream-json": "^1.8.0"
   },
   "devDependencies": {

src/parserRest.ts

@@ -1,8 +1,3 @@
-/**
- * JSON Rest parsing
- */
-
-import mapObject from "map-obj";
 import { parse } from "circ-json";
 
 import { toSnakeCase } from "./utils";
@@ -25,23 +20,46 @@ export const decamelizeKeys = (input: any) => {
     return input;
   }
 
-  const makeMapper = (parentPath?: string) => (key: string, value: any) => {
-    key = cachedDecamelize(key);
+  return transform(input);
 
-    if (isObject(value)) {
-      const path = parentPath === undefined ? key : `${parentPath}.${key}`;
+  function transform(value: any, parentPath?: string): any {
+    if (!isObject(value)) {
+      return value;
+    }
 
-      // @ts-ignore
-      value = mapObject(value, makeMapper(path));
-    } else {
-      value = cachedValueParser(key, parentPath, value);
+    if (Array.isArray(value)) {
+      const length = value.length;
+      const result = new Array(length);
+
+      for (let i = 0; i < length; i += 1) {
+        const item = value[i];
+        result[i] = isObject(item) ? transformObject(item, parentPath) : item;
+      }
+
+      return result;
     }
 
-    return [key, value];
-  };
+    return transformObject(value, parentPath);
+  }
 
-  // @ts-ignore
-  return mapObject(input, makeMapper());
+  function transformObject(obj: Record<string, any>, parentPath?: string) {
+    const output: Record<string, any> = {};
+
+    for (const key of Object.keys(obj)) {
+      const rawValue = obj[key];
+      const newKey = cachedDecamelize(key);
+
+      if (isObject(rawValue)) {
+        const nextParentPath =
+          parentPath === undefined ? newKey : `${parentPath}.${newKey}`;
+        output[newKey] = transform(rawValue, nextParentPath);
+      } else {
+        output[newKey] = cachedValueParser(newKey, parentPath, rawValue);
+      }
+    }
+
+    return output;
+  }
 };
 
 const cachedDecamelize = (key: string) => {

yarn.lock

@@ -3040,11 +3040,6 @@ makeerror@1.0.12:
   dependencies:
     tmpl "1.0.5"
 
-map-obj@^4.0.0:
-  version "4.3.0"
-  resolved "https://registry.npmjs.org/map-obj/-/map-obj-4.3.0.tgz"
-  integrity sha512-hdN1wVrZbb29eBGiGjJbeP8JbKjq1urkHJ/LIP/NY48MZ1QVXUsQBV1G1zvYFHn1XE06cwjBsOI2K3Ulnj1YXQ==
-
 math-intrinsics@^1.1.0:
   version "1.1.0"
   resolved "https://registry.npmjs.org/math-intrinsics/-/math-intrinsics-1.1.0.tgz"