You can lock your Node Editor view so that any new nodes you create do not appear in the graph.
Click this icon 
to unlock your view. The Node Editor view is locked by default.
When in locked mode , you can still use the following methods to create new nodes, and they appear in the Node Editor:
, you can still use the following methods to create new nodes, and they appear in the Node Editor: - Tab key. See Create a node for more information.
- With the mouse, middle-drag a node from the create node pane (click
on the toolbar) or Outliner to the Node Editor (drag and drop creation).
Note: You can still perform delete and undo in locked mode.
However, nodes created in the scene view, or by clicking in the create node pane (in other words, not drag and drop creation), do not appear in the Node Editor.
Tip: You can also lock the view by disabling the Options > Add to Graph on Create option under the Node Editor Options menu or from the Node Editor work area marking menu. See Node Editor Options menu and Node Editor marking menus for more information.