Require Node.js 12 and drop UMD build

[sindresorhus]

I have decided to target Node.js 12 and drop the UMD build. Node.js 10 will be obsolete in a few months anyway.

This lets us go full ESM, which reduces the chances of problems as some bundlers cannot handle exports in package.json.

[sindresorhus]

Any ideas why this doesn't work? I'm still getting:

  browser › headers are preserved when input is a Request and there are searchParams in the options

  Rejected promise returned by test. Reason:

  Error {
    message: `Evaluation failed: TypeError: window.ky is not a function␊
        at __puppeteer_evaluation_script__:6:17`,
  }

  › __puppeteer_evaluation_script__:6:17
  › ExecutionContext._evaluateInternal (node_modules/puppeteer/lib/cjs/puppeteer/common/ExecutionContext.js:217:19)
  › ExecutionContext.evaluate (node_modules/puppeteer/lib/cjs/puppeteer/common/ExecutionContext.js:106:16)
  › file://test/browser.js:331:2
  › withPage (file://test/helpers/with-page.js:7:3)

in the browser tests.

[sholladay]

An educated guess... I think what's happening is that the browser is trying to load /index.js but there's no such route on the server in the tests. We didn't need a route prior to this PR because Puppeteer itself (on the Node.js side) was reading the file at path from the filesystem and injecting it inline as a string in a script tag.

[sindresorhus]

I managed to solve it. Really weird that the import call didn't throw though.

[sholladay]

This could break some edge cases, including the scenario from #203 and #202. Basically, I've seen cases where some of the globals we rely on were actually defined on different objects (i.e. not true globals), particularly in mocked test environments.

That said, we're less reliant on these globals since the last time I had any issues and now that Node.js actually has globalThis and I can do globalThis.window = globalThis... maybe it won't be a problem? I'm not entirely sure. I'm 👍 on simplifying this, but let's definitely mark it as a breaking change.

[sindresorhus]

Let's try and see. I would prefer for us to not have to have lots of workarounds for weird use-cases.

[sindresorhus]

I'm skipping the browser tests on CI for now. They always succeed locally, but randomly fail with Evaluation failed: TypeError: window.ky is not a function on CI. Feels like some kind of internal race issue in Puppeteer. I wasted a lot of time trying to debug this.

[rifler]

I'm sorry, but full esm means, that consumers should rewrite their code to esm too, otherwise it would be error require of es modules is not supported

[szmarczak]

@rifler You need to use import instead of require.