如何使用 javascript 在 2 层 JSON 中获取特定值。？

Question

我的 JSON 数据类似于以下示例。

{"0":{"access_token":"ya29.MgCIagT8PCpkRSIAAAAl-XYEA37OjX_GBAv4so6qv0Gowc5XD3Bp6MuwYAPmnNuwgz7ElXsRwXqGWL4aZpA","token_type":"Bearer","expires_in":"3600","scope":"https://www.googleapis.com/auth/plus.login https://www.googleapis.com/auth/plus.moments.write https://www.googleapis.com/auth/plus.me https://www.googleapis.com/auth/plus.profile.agerange.read https://www.googleapis.com/auth/plus.profile.language.read https://www.googleapis.com/auth/plus.circles.members.read","id_token":"eyJhbGciOiJSUzI1NiIsImtpZCI6IjRiMTEyMDUxY2M3ZmJmZWI0MmI3OWU0OWVkNDIwYTQ2Yjk1YTkwYTQifQ.eyJpc3MiOiJhY2NvdW50cy5nb29nbGUuY29tIiwic3ViIjoiMTE1NTIzMTUwNzczOTI1MTk0ODE4IiwiYXpwIjoiMTUwNDU0MzcwMTUxLWM4aGFubnV0NXE0cWhrNzM3bTB0MGVpNjBnM29zcjlhLmFwcHMuZ29vZ2xldXNlcmNvbnRlbnQuY29tIiwiYXRfaGFzaCI6IkszS1UyNjRBY3QxeWhfbXZ6TlI4UXciLCJhdWQiOiIxNTA0NTQzNzAxNTEtYzhoYW5udXQ1cTRxaGs3MzdtMHQwZWk2MGczb3NyOWEuYXBwcy5nb29nbGV1c2VyY29udGVudC5jb20iLCJjX2hhc2giOiIxOE9qaWtOM1NOWnh6VVNCQWkxZnJBIiwiaWF0IjoxNDAzOTg1ODQzLCJleHAiOjE0MDM5ODk3NDN9.YWqarKgkXIi1u8v3jZ5726GHeTUn14Vvh3NryaDVg6M-e8a4a74HqhVt6zixjq35Minc_cCMxSOKIotBZDp1aG0_qKypRnatOJr3SM1-wIz779FNMUbS31y53S9NRHxOiE41Dtwvyyc6Np69K1RKT8f4FHM96XzAnLiJolAmT00","num_sessions":"1","session_state":"04e6cecd3bb8aa7993e6867475eaa3c9f50f9e19..48fa","client_id":"150454370151-c8hannut5q4qhk737m0t0ei60g3osr9a.apps.googleusercontent.com","response_type":"code token id_token gsession","issued_at":"1403986143","expires_at":"1403989743","_aa":"0"}}

并且obj.access_token 没有检索其值，而是返回"undefined".

Answer 1

试试这个：

var j = {"0":{"access_token":"ya29.MgCIagT8PCpkRSIAAAAl-XYEA37OjX_GBAv4so6qv0Gowc5XD3Bp6MuwYAPmnNuwgz7ElXsRwXqGWL4aZpA","token_type":"Bearer","expires_in":"3600","scope":"https://www.googleapis.com/auth/plus.login https://www.googleapis.com/auth/plus.moments.write https://www.googleapis.com/auth/plus.me https://www.googleapis.com/auth/plus.profile.agerange.read https://www.googleapis.com/auth/plus.profile.language.read https://www.googleapis.com/auth/plus.circles.members.read","id_token":"eyJhbGciOiJSUzI1NiIsImtpZCI6IjRiMTEyMDUxY2M3ZmJmZWI0MmI3OWU0OWVkNDIwYTQ2Yjk1YTkwYTQifQ.eyJpc3MiOiJhY2NvdW50cy5nb29nbGUuY29tIiwic3ViIjoiMTE1NTIzMTUwNzczOTI1MTk0ODE4IiwiYXpwIjoiMTUwNDU0MzcwMTUxLWM4aGFubnV0NXE0cWhrNzM3bTB0MGVpNjBnM29zcjlhLmFwcHMuZ29vZ2xldXNlcmNvbnRlbnQuY29tIiwiYXRfaGFzaCI6IkszS1UyNjRBY3QxeWhfbXZ6TlI4UXciLCJhdWQiOiIxNTA0NTQzNzAxNTEtYzhoYW5udXQ1cTRxaGs3MzdtMHQwZWk2MGczb3NyOWEuYXBwcy5nb29nbGV1c2VyY29udGVudC5jb20iLCJjX2hhc2giOiIxOE9qaWtOM1NOWnh6VVNCQWkxZnJBIiwiaWF0IjoxNDAzOTg1ODQzLCJleHAiOjE0MDM5ODk3NDN9.YWqarKgkXIi1u8v3jZ5726GHeTUn14Vvh3NryaDVg6M-e8a4a74HqhVt6zixjq35Minc_cCMxSOKIotBZDp1aG0_qKypRnatOJr3SM1-wIz779FNMUbS31y53S9NRHxOiE41Dtwvyyc6Np69K1RKT8f4FHM96XzAnLiJolAmT00","num_sessions":"1","session_state":"04e6cecd3bb8aa7993e6867475eaa3c9f50f9e19..48fa","client_id":"150454370151-c8hannut5q4qhk737m0t0ei60g3osr9a.apps.googleusercontent.com","response_type":"code token id_token gsession","issued_at":"1403986143","expires_at":"1403989743","_aa":"0"}};
alert(j["0"].access_token);