babel-plugin-strip-parcel-hmr

An experimental Babel plugin for removing hot module replacement (HMR) code from production bundles created with Parcel.

Currently the following syntaxes are supported:

• Tests in if and else statements
• Tests in the ternary ?: operator
• Checking for HMR with module.hot and module['hot']
• Checking for HMR with typeof module.hot
• Checking for HMR with 'hot' in module
• Negating tests with !

Examples

In

if (module.hot) {
  module.hot.accept(() => {
    // update module
  });
}

const value = module.hot ? 'in development' : 'in production';

// rest of the code here

Out

const value = 'in production';

// rest of the code here

In

if (!module.hot) {
  // only when HMR is disabled
}

Out

{
  // only when HMR is disabled
}

Installation

npm install @emmiep/babel-plugin-strip-parcel-hmr

Usage

.babelrc

{
  "env": {
    "production": {
      "plugins": [
        "@emmiep/babel-plugin-strip-parcel-hmr"
      ]
    }
  }
}

The plugin would normally only be used for the production environment (which is automatically set when running parcel build) to preserve the HMR code during development. This is accomplished by using the env option in .babelrc as shown above.

Options

objectName

string, defaults to module.

The name of the global object containing a property (propertyName) used when checking if HMR is enabled.

propertyName

string, defaults to hot.

The name of the property used when checking if HMR is enabled.

Caveats

Currently Parcel is not implementing tree-shaking, which means functions only used during development for HMR will still be included in the production bundles unless they're defined inside if statements testing for HMR. For instance any module imported using the ES6 import keyword will always be included in the production bundle.