refactor(lib): Add support for Node.js >= v4

fix #2

.travis.yml

@@ -4,5 +4,7 @@ node_js:
   - v8
   - v7
   - v6
+  - v5
+  - v4
 after_success:
   - './node_modules/.bin/nyc report --reporter=text-lcov | ./node_modules/.bin/coveralls'

index.js

@@ -23,18 +23,20 @@
  * //=> [{v: 1}, {v: 3}]
  */
 function toggleInArray(arr, value, predicate) {
-	let includes = false;
 	predicate = predicate || defaultPredicate;
+	var includes = false;
+	var result = [];
+
+	for (var i = 0, length = arr.length; i < length; i += 1) {
+		var item = arr[i];
 
-	const result = arr.reduce((acc, item) => {
 		if (predicate(item, value)) {
 			includes = true;
-			return acc;
+			continue;
 		}
 
-		acc.push(item);
-		return acc;
-	}, []);
+		result.push(item);
+	}
 
 	if (!includes) {
 		result.push(value);

package.json

@@ -6,11 +6,11 @@
   "repository": "VovanR/toggle-in-array",
   "author": "Vladimir Rodkin <mail@vovanr.com> (http://vovanr.com/)",
   "engines": {
-    "node": ">=6"
+    "node": ">=4"
   },
   "scripts": {
     "prepush": "npm test",
-    "test": "xo && nyc ava",
+    "test": "xo --no-esnext && nyc ava",
     "tdd": "ava -w",
     "release-patch": "mversion patch",
     "release-minor": "mversion minor",