When you select a node under the Elements tab, Chrome DevTools adds == $0 right after the node.
In give us a hint that we can use the $0 expression to access the selected node.
You can invoke any DOM APIs from $0.
The DevTools remembers the last five selected nodes. In addition to $0, we can use $1, $2, $3 and $4 to access the last selected nodes.
You also can right-click the node, and choose Store as global variable from the context menu. DevTools creates a variable, temp1 for example, to represent the selected node.
Now you can use temp1 to manage the node in the same way as $0.