javascript - Determine user network environment

Question

How does js determine whether the user's network is useful? That is, I want to determine whether the user can use the external network? And make sure he has access to the Internet? God, please help me. . .

Answer 1

Request an external network address in the background and see if it can be returned normally.

Answer 2

$.ajax({
    url: '/',
    success: res => alert('应该有网'),
    error: () => alert('应该没网')
}); 

Want to try it?

Answer 3

You can use it directly, or learn from https://www.npmjs.com/package/ping