"Top-level await is not available in the configured target environment"

[o-t-w]

I thought that ESBuild was meant to be able to transpile code so it works in older browsers? Or is the point of target just to show me errors telling me I can't use certain features?

My output format is ES modules, in which I thought top level await is meant to be able to work?

require('esbuild').build({
  entryPoints: ['./src/new-js/international.js', './src/new-js/homepage.js'],
  bundle: true,
  minify: true,
  format: 'esm',
  outdir: 'build/js/new-js',
  target: ['chrome75', 'firefox70', 'safari11'],
}).catch(() => process.exit(1));

[evanw]

Some language features can be transpiled but others can't be. Top-level await can't really be transpiled because there's no equivalent older syntax. Up until the introduction of top-level await, all ESM module evaluation was synchronous. There was no way to insert an asynchronous step at the top-level.

[bisubus]

@evanw This requires a bundler to be aware of top-level awaits, but I don't see fundamental problems with this. Webpack supports this, doesn't it? I guess an equivalent is that every module export is wrapped with async IIFE.

[evanw]

Webpack doesn't even support the ESM output format at all I think (open issue: webpack/webpack#2933) so it's not equivalent. I'm planning to add support for top-level await to the IIFE output format for esbuild, in which case this should work.

[evanw]

Closing this as a duplicate of #253, which is the general open issue for top-level await support. I'm using that issue to represent adding top-level await support to the IIFE format.