Conditional Node code bundled for browser platform

[elefeint]

Is it possible with esbuild to bundle javascript that contains conditionally gated Node code for browser target? Currently, it results in an error message -- The package "module" wasn't found on the file system but is built into node. Are you trying to bundle for node? You can use "platform: 'node'" to do that, which will remove this error. While switching the target to node would work, it's also not semantically correct and will probably cause more issues in the future, since this bundle really was intended for browser use (we have another bundle being generated from the same source code for the node target).

  if (ENVIRONMENT_IS_NODE) {
    const {createRequire: createRequire} = await import("module");
    var fs = require("fs");
    // ... other code ...
  } else {
    // browser-specific alternative
  }

The reason this came up now is that emscripten 3.1.27 changed the way they output multi-environment javascript to use an explicit import('module'), which caused previously successful esbuild bundling to fail. I've tried setting the treeShaking option, hoping the unused conditional will be pruned, but it did not seem to have an effect.

Minimal reproducer attached.

esbuild_conditional_node.tar.gz

[evanw]

What about --external:module? Documentation: https://esbuild.github.io/api/#external

[elefeint]

This worked perfectly! This was our exact use-case; I missed it when reading the docs.

a package may contain code that only runs in node but you will only be using that package in the browser

Thank you very much!