From 8f49b12d850d4c6033d8a828f993658636f33a98 Mon Sep 17 00:00:00 2001 From: Guy Bedford Date: Fri, 10 Jul 2020 23:37:20 -0700 Subject: [PATCH] doc: clarify conditional exports guidance MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit PR-URL: https://github.com/nodejs/node/pull/34306 Reviewed-By: Rich Trott Reviewed-By: James M Snell Reviewed-By: Michaƫl Zasso Reviewed-By: Jan Krems --- doc/api/esm.md | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/doc/api/esm.md b/doc/api/esm.md index 0691a5cce3d5da..254d7240a733b5 100644 --- a/doc/api/esm.md +++ b/doc/api/esm.md @@ -456,7 +456,7 @@ Conditional exports can also be extended to exports subpaths, for example: "exports": { ".": "./main.js", "./feature": { - "browser": "./feature-browser.js", + "node": "./feature-node.js", "default": "./feature.js" } } @@ -464,8 +464,16 @@ Conditional exports can also be extended to exports subpaths, for example: ``` Defines a package where `require('pkg/feature')` and `import 'pkg/feature'` -could provide different implementations between the browser and Node.js, -given third-party tool support for a `"browser"` condition. +could provide different implementations between Node.js and other JS +environments. + +When using environment branches, always include a `"default"` condition where +possible. Providing a `"default"` condition ensures that any unknown JS +environments are able to use this universal implementation, which helps avoid +these JS environments from having to pretend to be existing environments in +order to support packages with conditional exports. For this reason, using +`"node"` and `"default"` condition branches is usually preferable to using +`"node"` and `"browser"` condition branches. #### Nested conditions @@ -479,11 +487,11 @@ use in Node.js but not the browser: { "main": "./main.js", "exports": { - "browser": "./feature-browser.mjs", "node": { "import": "./feature-node.mjs", "require": "./feature-node.cjs" - } + }, + "default": "./feature.mjs", } } ```