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npmsemantic-versioning

What does OR operator mean in package.json for an npm package's version?

What is the significance of OR operator (||) between npm versions?

Eg:

"dependencies": {
  "@jupyter-widgets/base": "^1.1.10 || ^2 || ^3"
}

I see version 3 is always installed for me.

Solution

  • As you might expect, the double pipe OR operator allows you to create a semver that consists of other semver strings. If any of the operands to the OR are satisfied, the expression is satisfied.

    In the context of NPM dependencies, the package manager will usually use the most recent version of the package that satisfies the semver string in package.json AND works in the current environment. For example, if a package is compatible with a certain dependency at v2 and v3 but not v1 or v4, using ^2 || ^3 in the semver is best. For most people, v3 will be installed by the package manager, but if v3 is incompatible with macOS, the package manager will install v2 for macOS users.

    Effectively, the OR operator offers the package manager more options when deciding which dependencies to install, but in modern JavaScript there are few reasons to use it because you will rarely be able to use different major versions of any given package.