Is there a way to disable inspection for one file opened in the editor? I occasionally open large library file in the editor to inspect its source code, and don't want IDEA to run inspections on this particular file.
Use Hector the Inspector guy. You can access it by clicking on "guy in a hat" icon in Status Bar or via Code | Configure Current File Analysis...
from the main menu.
Once there you can move the "Highlighting Level" slider from "Inspections" to "Syntax" .. or even "None" in case of a large or complex file.
Notes:
Settings here affect current file only (excludes "Power Save Mode" option)
Depending on a file, you may have multiple sliders (e.g. in .php
file you will see separate sliders for HTML and PHP languages: this may change depending on some other settings):
P.S. If your file is actually part of the library (PHP or JavaScript; "Library" in terms of IDE, of course) then they by default should not have inspections enabled in them:
UPDATE 2021-06-11:
Hector the Inspector has been removed from the status bar since 2020.2 version or so. You can get it back by installing Hector the Inspector plugin from Settings/Preferences | Plugins