Support sorting of objects inside deep arrays

index.js

@@ -2,14 +2,36 @@
 const isPlainObj = require('is-plain-obj');
 
 module.exports = (obj, opts = {}) => {
-	if (!isPlainObj(obj)) {
-		throw new TypeError('Expected a plain object');
-	}
-
 	const {deep} = opts;
 	const seenInput = [];
 	const seenOutput = [];
 
+	const deepSortArray = x => {
+		const seenIndex = seenInput.indexOf(x);
+
+		if (seenIndex !== -1) {
+			return seenOutput[seenIndex];
+		}
+
+		const ret = [];
+		seenInput.push(x);
+		seenOutput.push(ret);
+
+		ret.push(...x.map(y => {
+			if (Array.isArray(y)) {
+				return deepSortArray(y);
+			}
+
+			if (isPlainObj(y)) {
+				return sortKeys(y);
+			}
+
+			return y;
+		}));
+
+		return ret;
+	};
+
 	const sortKeys = x => {
 		const seenIndex = seenInput.indexOf(x);
 
@@ -27,7 +49,7 @@ module.exports = (obj, opts = {}) => {
 			const val = x[key];
 
 			if (deep && Array.isArray(val)) {
-				ret[key] = val.map(y => isPlainObj(y) ? sortKeys(y) : y);
+				ret[key] = deepSortArray(val);
 				continue;
 			}
 
@@ -37,5 +59,13 @@ module.exports = (obj, opts = {}) => {
 		return ret;
 	};
 
-	return sortKeys(obj);
+	if (isPlainObj(obj)) {
+		return sortKeys(obj);
+	}
+
+	if (Array.isArray(obj)) {
+		return deep ? deepSortArray(obj) : obj;
+	}
+
+	throw new TypeError('Expected a plain object or an array');
 };

test.js

@@ -53,3 +53,33 @@ test('deep option', t => {
 	t.deepEqual(sortKeys({c: {c: 0, a: 0, b: 0}, a: 0, b: 0, z: [9, 8, 7, 6, 5]}, {deep: true}), {a: 0, b: 0, c: {a: 0, b: 0, c: 0}, z: [9, 8, 7, 6, 5]});
 	t.deepEqual(Object.keys(sortKeys({a: [{b: 0, a: 0}]}, {deep: true}).a[0]), ['a', 'b']);
 });
+
+test('deep arrays', t => {
+	const obj = {
+		b: 0,
+		a: [
+			{b: 0, a: 0},
+			[{b: 0, a: 0}]
+		]
+	};
+	const arr = [
+		[{b: 0, a: 0}]
+	];
+	obj.a.push(obj);
+	obj.a[1].push(obj.a[1]);
+
+	t.notThrows(() => {
+		sortKeys(arr);
+		sortKeys(arr, {deep: true});
+		sortKeys(obj, {deep: true});
+	});
+
+	const sorted = sortKeys(obj, {deep: true});
+	t.is(sorted.a[2], sorted);
+	t.is(sorted.a[1][1], sorted.a[1]);
+	t.deepEqual(Object.keys(sorted), ['a', 'b']);
+	t.deepEqual(Object.keys(sorted.a[0]), ['a', 'b']);
+	t.deepEqual(Object.keys(sorted.a[1][0]), ['a', 'b']);
+
+	t.deepEqual(Object.keys(sortKeys(arr, {deep: true})[0][0]), ['a', 'b']);
+});