@jsenv/import-map

jsenv-import-map

Helpers to implement importMap

Table of contents

• Presentation
• Usage
  • composeTwoImportMaps
  • normalizeImportMap
  • resolveImport
• Installation

Presentation

@jsenv/import-map can be used to implement the behaviour of importMap as described in the specification. It is written using es modules and is compatible with Node.js.

— see importMap spec

Usage

@jsenv/import-map exports are documented in this section.

composeTwoImportMaps

composeTwoImportMaps takes two importMap and return a single importMap being the composition of the two.
Implemented by src/composeTwoImportMaps.js

import { composeTwoImportMaps } from "@jsenv/import-map"

const importMap = composeTwoImportMaps(
  {
    imports: {
      foo: "bar",
    },
  },
  {
    imports: {
      foo: "whatever",
    },
  },
)

console.log(JSON.stringify(importMap, null, "  "))

{
  "imports": {
    "foo": "whatever"
  }
}

normalizeImportMap

normalizeImportMap returns an importMap resolved against an url and sorted.
Implemented by src/normalizeImportMap.js

import { normalizeImportMap } from "@jsenv/import-map"

const importMap = normalizeImportMap(
  {
    imports: {
      foo: "./bar",
      "./ding.js": "./dong.js"
    },
  },
  "http://your-domain.com",
)

console.log(JSON.stringify(importMap, null, '  ')

{
  "imports": {
    "foo": "http://your-domain.com/bar",
    "http://your-domain.com/ding.js": "http://your-domain.com/dong.js"
  }
}

resolveImport

resolveImport returns an import url applying an importMap to specifier and importer.
Implemented by src/resolveImport.js

import { resolveImport } from "@jsenv/import-map"

const importUrl = resolveImport({
  specifier: "../index.js",
  importer: "http://domain.com/folder/file.js",
  importMap: {
    imports: {
      "http://domain.com/index.js": "http://domain.com/main.js",
    },
  },
})

console.log(importUrl)

http://domain.com/main.js

The provided importMap must be resolved and sorted to work as expected. You can use normalizeImportMap to do that.

Installation

If you never installed a jsenv package, read Installing a jsenv package before going further.

This documentation is up-to-date with a specific version so prefer any of the following commands

npm install --save-dev @jsenv/import-map@6.2.0

yarn add --dev @jsenv/import-map@6.2.0