Dynamic import not resolved during build about esbuild HOT 1 OPEN

This is because "/js/pages/404.js" is an absolute path. esbuild runs its node-behavior resolver against those paths in import(path) and require(path) and includes (bundles) them in the bundle. There's no such file with the absolute path in your file system.

If it is in a single build (i.e. in one esbuild.build() call), you can reference 404.js with relative path, e.g. "./pages/404.js".

On the other hand, you may mark this path as external through a plugin, roughly look like this:

var custom_external_plugin = {
  name: "custom-external",
  setup({ onResolve }) {
    onResolve({ filter: /404\.js$/ }, args => {
      return { path: args.path, external: true }
    })
  }
}

from esbuild.