Azure "Web apps" service: auto-install npm modules from package.json
Azure does not install the devDependencies.If you need them on production, it is not devDependencies but dependencies
In your package.json, devDependencies should be renamed to dependencies
This kind of thing appens when you npm install --save-dev.
Production dependency (needed to run): npm install --save
Otherwise (build tools, jshint, etc.): npm install --save-dev