npm update seems to update dependencies, but how about updating devDependencies.
I can. DevDependencies be installed by running npm install, but it does not apply to npm update.
The Check the Updates-install-npm ( https://www.npmjs.org/package/npm-check-updates ), then jump into your project folder and run:
npm-check-updates
And update and save changes to the package.json file:
npm-check-updates -u