I’ve edited your post for readability. When you enter a code block into a forum post, please precede it with a separate line of three backticks and follow it with a separate line of three backticks to make it easier to read.
You can also use the “preformatted text” tool in the editor (</>) to add backticks around text.
when you use bracket notation, the content is evaluated. you can use usersObj[x] because x is a variable with a value. you do not have an online variable, so usersObj[x][online] is like usersObj[x][undefined]