@balena/es-version

@balena/es-version

This module allows specifying a target es version for other modules to require, currently supported target versions:

• es3 (default)
• es5
• es2015
• es2016
• es2017
• es2018
• es2019
• es2020
• es2021
• es2022
• esnext

Usage as a client

• Add @balena/es-version to your package.json with a ^ version specifier, eg

"@balena/es-version": "^1.0.0",

Note: If using locked dependences, eg package-lock.json/npm-shrinkwrap.json/etc, then make sure to also dedupe the module so that the same instance of the module is used everywhere.

• Within your module require it before anything else and set the desired version:

// Must be set before the first require of an @balena/es-version supporting module
require('@balena/es-version').set('es5');

and then the closest matching version will be used by any module that supports choosing the target version, with the priority being:

• exact match
• closest match under the desired version
• lowest supported version

Usage as a module provider

• Add @balena/es-version to your package.json with a ^ version specifier, eg

"@balena/es-version": "^1.0.0",

• Generate builds for the es versions you wish to support along with types for the shim you'll create, eg

"build-es5": "tsc --target es5 --outDir es5",
"build-es2015": "tsc --target es2015 --outDir es2015",
"build-es2018": "tsc --target es2018 --outDir es2018",
"build-types": "tsc --emitDeclarationOnly --outDir .",
"build": "npm run build-es5 && npm run build-es2015 && npm run build-es2018 && npm run build-types",

• Create a shim to use as your entry-point which loads the desired version, eg

// First get the es version to use:
var esVersion = require('@balena/es-version').get(['es5', 'es2015', 'es2018');
// Then include/return the correct version of your module, eg
module.exports = module.exports = require('./' + esVersion);

Note: This must be compatible with your lowest supported es version

• Point your package.json to the new shim and types, eg

"main": "index.js",
"types": "index.d.ts",

• It is also recommended to add a "browser" entry to a fixed es version in your package.json in order to support browser bundlers with default config, eg

"browser": "es5"