前端从后端获取错误数据

For example:

Go back-end sends:

map{"1": 0, "2": 1}

JavaScript front-end uses fetch to get data from back-end:

{"2": 1, "1": 0, "3": 1}

Is it possible that front-end got data which has one (or two) more element accidentally?

it's impossible, there must be something wrong in your code. two options in my opinion.

1. make sure your Go Back-end sends right data.

2. capture data using software wireshark.