til/javascript/pre-and-post-hooks-for-yarn-scripts.md

Pre And Post Hooks For Yarn Scripts

In yarn v1, there is a special syntax for script names that allows you to define pre and post hooks.

For instance, if you have a build script, you can define a prebuild and/or a postbuild script as well. Then, anytime you invoke yarn build, the prebuild script will be automatically run before build and the postbuild script be automatically run after build.

This pre{script} and post{script} syntax works for any script.

{
  "scripts": {
    "predeploy": "node pre-deploy-steps"
    "deploy": "my-framework deploy",
    "postdeploy": "node post-deploy-steps"
  }
}

This syntax may lead to unexpected script invocations. For instance, a preserve script will run ahead of a serve script even though those were probably intended to be unrelated scripts. This is, in part, why this syntax is no longer support in yarn v2.

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