问题
I want to know what is the == $0 in developer tool, it is marked by red in the screenshot.
I found this == $0 in code of every website in developer tool and want to know what is this?
回答1:
$0 refers to the current selected element in your source.
It means that you can access to this element in the DevTools console by simply typing:
$0
From there, you can do whatever you like with this element, by using Javascript DOM API.
See Chrome DevTools reference
回答2:
I personally am not seeing this, but $0 usually refers to the element currently inspected.
Try it out by right-clicking this comment and choose "Inspect element" in Google Chrome. If you pop over to the console and type out $0, it will select the element in the page and print it out in the console.
来源：https://stackoverflow.com/questions/37115354/what-is-0-in-developer-tool-after-the-end-of-every-line-of-code