It is also at least some level of defense against malicious npm packages (doesn't eliminate threat completely, but at least less sophisticated attacks will be thwarted).
CSP headers are a very useful tool and I encourage everyone to use them. They are a PITA to set up though. Fortunately at least Firefox clearly communicates in console log when a CSP rule is hit, and how to relax it (if it was by mistake).
Note that CSP can be set as META tags too. There's a gotcha though: if they are set in both places (HTTP headers and HTML META tags), an intersection of the rules is used.
CSP headers are a very useful tool and I encourage everyone to use them. They are a PITA to set up though. Fortunately at least Firefox clearly communicates in console log when a CSP rule is hit, and how to relax it (if it was by mistake).
Note that CSP can be set as META tags too. There's a gotcha though: if they are set in both places (HTTP headers and HTML META tags), an intersection of the rules is used.