This command is similar to npm install, except
it's meant to be used in automated environments such as test platforms,
continuous integration, and deployment -- or any situation where you want
to make sure you're doing a clean install of your dependencies.
npm ci will be significantly faster when:
There is a package-lock.json or npm-shrinkwrap.json file.
The node_modules folder is missing or empty.
In short, the main differences between using npm install and npm ci are:
The project must have an existing package-lock.json or
If dependencies in the package lock do not match those in package.json,
npm ci will exit with an error, instead of updating the package lock.
npm ci can only install entire projects at a time: individual
dependencies cannot be added with this command.
If a node_modules is already present, it will be automatically removed
before npm ci begins its install.
It will never write to package.json or any of the package-locks:
installs are essentially frozen.
Make sure you have a package-lock and an up-to-date install:
$ cd ./my/npm/project
added 154 packages in 10s
$ ls|grep package-lock
Run npm ci in that project
$ npm ci
added 154 packages in 5s
Configure Travis to build using npm ci instead of npm install: