3.7 What you need to know

JSPM "forks"

JSPM allows for multiple versions of installed dependencies. When two dependencies import two different versions of the same library, JSPM may detect a conflict which it calls a "fork". In this case it issues a warning like this:

Installed Forks

             github:systemjs/plugin-css 0.1.20 0.1.21

This example is taken from aurelia-skeleton-navigation 1.0.0-beta.1.2.2 (after installing the bridge) which has a dependency on font-awesome@^4.5.0 - itself depending on plugin-css@0.1.20. Notice lack of the ^ indicator, meaning that JSPM will install exactly this version.

When installing the bridge you install an indirect dependency of plugin-css@0.1.21 which Dogfalo/materialize depends on.

As the version numbers in both cases are static (no ^ indicator), both versions of plugin-css are installed, leading to a fork.

There are two options to resolve this:

• install with the --lock option

• use jspm resolve

Installing the bridge using --lock

The --lock option keeps existing dependencies locked during a JSPM installation. So if you know the installation will introduce a fork and you want to keep the installed version of a library, use jspm install --lock aurelia-materialize-bridge.

Using jspm resolve

JSPM has a builtin command to change every used version of a dependency to the version you want. In the case above you'd issue jspm resolve --only github:systemjs/plugin-css@0.1.21. Please note that you have to give JSPM an exact package of the form registry:pkg@version.