Implement a smarter deletion of properties when resizing an array.

jsproperty.c

@@ -237,3 +237,20 @@ const char *jsV_nextiterator(js_State *J, js_Object *iobj)
 	}
 	return NULL;
 }
+
+/* Walk all the properties and delete them one by one for arrays */
+
+void jsV_resizearray(js_State *J, js_Object *obj, unsigned int newlen)
+{
+	const char *s;
+	unsigned int k;
+	if (newlen < obj->u.a.length) {
+		js_Object *it = jsV_newiterator(J, obj);
+		while ((s = jsV_nextiterator(J, it))) {
+			k = jsV_numbertouint32(jsV_stringtonumber(J, s));
+			if (k >= newlen && !strcmp(s, jsV_numbertostring(J, k)))
+				jsV_delproperty(J, obj, s);
+		}
+	}
+	obj->u.a.length = newlen;
+}

jsrun.c

@@ -299,14 +299,9 @@ static void jsR_setproperty(js_State *J, js_Object *obj, const char *name, int i
 		if (!strcmp(name, "length")) {
 			double rawlen = js_tonumber(J, idx);
 			unsigned int newlen = jsV_numbertouint32(rawlen);
-			unsigned int oldlen = obj->u.a.length;
 			if (newlen != rawlen)
 				js_rangeerror(J, "array length");
-			for (k = newlen; k < oldlen; ++k) {
-				sprintf(buf, "%u", k);
-				jsV_delproperty(J, obj, buf);
-			}
-			obj->u.a.length = newlen;
+			jsV_resizearray(J, obj, newlen);
 			return;
 		}
 
@@ -340,7 +335,6 @@ static void jsR_defproperty(js_State *J, js_Object *obj, const char *name, int i
 
 static int jsR_delproperty(js_State *J, js_Object *obj, const char *name)
 {
-	// TODO: does delete follow prototype chain?
 	js_Property *ref = jsV_getownproperty(J, obj, name);
 	if (ref) {
 		if (ref->atts & JS_DONTDELETE)

jsvalue.h

@@ -120,6 +120,8 @@ void jsV_delproperty(js_State *J, js_Object *obj, const char *name);
 js_Object *jsV_newiterator(js_State *J, js_Object *obj);
 const char *jsV_nextiterator(js_State *J, js_Object *iobj);
 
+void jsV_resizearray(js_State *J, js_Object *obj, unsigned int newlen);
+
 /* jsdump.c */
 void js_dumpobject(js_State *J, js_Object *obj);
 void js_dumpvalue(js_State *J, js_Value v);