fix: deep assign should ignore inseparable object

index.js

@@ -11,6 +11,18 @@ function toObject(val) {
 	return Object(val);
 }
 
+function isInseparableObj(val) {
+	if (val instanceof Date) {
+		return true;
+	}
+
+	if (val instanceof RegExp) {
+		return true;
+	}
+
+	return false;
+}
+
 function assignKey(to, from, key) {
 	var val = from[key];
 
@@ -24,7 +36,7 @@ function assignKey(to, from, key) {
 		}
 	}
 
-	if (!hasOwnProperty.call(to, key) || !isObj(val)) {
+	if (!hasOwnProperty.call(to, key) || !isObj(val) || isInseparableObj(to[key])) {
 		to[key] = val;
 	} else {
 		to[key] = assign(Object(to[key]), from[key]);

test.js

@@ -79,6 +79,34 @@ test('support strings as targets', t => {
 	t.end();
 });
 
+test('support Date as targets', t => {
+	var target = fn({date: new Date()}, {date: 1446275964787});
+	t.is(target.date, 1446275964787);
+	t.is(target.date.constructor, Number);
+	t.end();
+});
+
+test('support Date as targets', t => {
+	var target = fn({date: new Date()}, {date: new Date(1446275964787)});
+	t.is(target.date.getTime(), 1446275964787);
+	t.is(target.date.constructor, Date);
+	t.end();
+});
+
+test('support RegExp as targets', t => {
+	var target = fn({regexp: /reg/}, {regexp: 'string'});
+	t.is(target.regexp.constructor, String);
+	t.is(target.regexp, 'string');
+	t.end();
+});
+
+test('support RegExp as targets', t => {
+	var target = fn({regexp: /reg/}, {regexp: /new/});
+	t.is(target.regexp.constructor, RegExp);
+	t.is(target.regexp.test('new'), true);
+	t.end();
+});
+
 test('support arrays as targets', t => {
 	var target = {a: ['many']};
 	var source = {a: []};