What does { content: [Circular] } mean in JavaScript?

Question

My code was:

var chineseBox = {};
chineseBox.content = chineseBox;

and it returned:

{ content: [Circular] }

Answer 1

Your object contains a circular reference. If you tried to print (or serialize) this object you would end up in an infinite loop

{content: {content: {content ...

Instead, your system was smart enough to notice the circularity and protect itself against it.