make it work on older browsers

package.json

@@ -42,9 +42,11 @@
     "node": ">=8"
   },
   "dependencies": {
+    "brackets2dots": "^1.1.0",
+    "curry2": "^1.0.3",
     "deep-equal": "1.0.1",
-    "predicate": "1.2.0",
-    "selectn": "1.1.2"
+    "dotsplit.js": "^1.1.0",
+    "predicate": "1.2.0"
   },
   "devDependencies": {
     "atob": "^2.0.3",

src/checkField.js

@@ -1,4 +1,4 @@
-import predicate from "predicate";
+import predicate from "predicate/dist/predicate";
 import { isObject } from "./utils";
 
 import { AND, NOT, OR } from "./constants";

src/conditionsMeet.js

@@ -35,8 +35,8 @@ export default function conditionsMeet(condition, formData) {
     } else {
       let refVal = selectRef(ref, formData);
       if (Array.isArray(refVal)) {
-        let condMeatOnce = refVal.some(
-          val => (isObject(val) ? conditionsMeet(refCondition, val) : false)
+        let condMeatOnce = refVal.some(val =>
+          isObject(val) ? conditionsMeet(refCondition, val) : false
         );
         // It's either true for an element in an array or for the whole array
         return (

src/selectn.js

@@ -0,0 +1,43 @@
+"use strict";
+
+var curry2 = require("curry2");
+var dotted = require("brackets2dots");
+var splits = require("dotsplit.js");
+
+module.exports = curry2(selectn);
+
+/**
+ * Curried property accessor function that resolves deeply-nested object properties via dot/bracket-notation
+ * string path while mitigating `TypeErrors` via friendly and composable API.
+ *
+ * @param {String|Array} path
+ * Dot/bracket-notation string path or array.
+ *
+ * @param {Object} object
+ * Object to access.
+ *
+ * @return {Function|*|undefined}
+ * (1) returns `selectn/1` when partially applied.
+ * (2) returns value at path if path exists.
+ * (3) returns undefined if path does not exist.
+ */
+function selectn(path, object) {
+  var idx = -1;
+  var seg = splits(dotted(path));
+  var end = seg.length;
+
+  if (!end) {
+    return undefined;
+  }
+
+  var ref = object;
+
+  while (++idx < end) {
+    if (Object(ref) !== ref) {
+      return undefined;
+    }
+    ref = ref[seg[idx]];
+  }
+
+  return typeof ref === "function" ? ref() : ref;
+}

src/utils.js

@@ -1,4 +1,4 @@
-import selectn from "selectn";
+import selectn from "./selectn";
 
 export function normRef(ref) {
   return ref.replace(/\$/g, ".");

src/validation.js

@@ -1,4 +1,4 @@
-import predicate from "predicate";
+import predicate from "predicate/dist/predicate";
 import {
   flatMap,
   isObject,

test/predicate.test.js

@@ -1,4 +1,4 @@
-import predicate from "predicate";
+import predicate from "predicate/dist/predicate";
 import Engine from "../src/Engine";
 
 test("equal work with same strings", function() {

test/selectn.test.js

@@ -1,20 +1,14 @@
-import selectn from "selectn";
+import selectn from "../src/selectn";
 
-test("selectn on array", function() {
+test("selectn", function() {
   let a = {
     medications: {
       type: "A",
+      fn: () => "B",
     },
   };
 
   expect(selectn("medications.type", a)).toEqual("A");
-
-  // let obj = {
-  //   medications: [
-  //     { type: "A" },
-  //     { type: "B" },
-  //     { type: "C" }
-  //   ]
-  // };
-  //expect(selectn("medications.type", obj)).toEqual(["A", "B", "C"]);
+  expect(selectn("medications.fn", a)).toEqual("B");
+  expect(selectn("", a)).toEqual(undefined);
 });

test/utils.test.js

@@ -72,7 +72,10 @@ test("extract referenced schema", () => {
     },
   };
 
-  let { definitions: { medication }, properties: { registration } } = schema;
+  let {
+    definitions: { medication },
+    properties: { registration },
+  } = schema;
 
   expect(isRefArray("medications", schema)).toBeTruthy();
   expect(extractRefSchema("medications", schema)).toEqual(medication);

test/validation.predicates.test.js

@@ -1,4 +1,4 @@
-import predicate from "predicate";
+import predicate from "predicate/dist/predicate";
 import { listInvalidPredicates } from "../src/validation";
 
 let schema = {