nodejs json 解析

arrMongoDatabases={    "blog":["php","test"],    "study":["java","mongo"]}var arrMongodb = JSON.stringify(arrMongoDatabases);var arr= JSON.parse(arrMongodb);for(db in arr){var db = db;//get db like "blog"var coll = arr[db];//get collections as a arrayfor(var i=0;i < coll.length;i++){console.log(coll[i]);//get any single item}console.log("-----------")}console.log(arr.blog[0]); // get "php"console.log(arr.study);//["java","mongo"]