Node < v16 do not provide a global atob() function for decoding base64 strings, and must use Buffer.from() instead. Furthermore, Buffer.from(str, 'base64').toString() is much faster than atob() in Node. Thus, prefer to use Buffer.from() if possible.

Description

This fixes #8620 for Vite 3. The bug is caused because Vite generates code that uses atob(), which is available only on Node.js 16+. This PR solves this by:

• Use Buffer.from() if it exists. This is faster than atob() (see below), so the code prioritizes it.
• Check for existence of atob() before using it.
• If neither options are available, throw an Error.

Note that Buffer.from() is much faster than atob():

// Node v16.15.1

> var bigStr = btoa('1234567890abcdefghijklmnopqrstuvwxyz'.repeat(100000));
> console.time('atob'); atob(bigStr); console.timeEnd('atob');
atob: 117.196ms
> console.time('Buffer.from'); Buffer.from(bigStr, 'base64').toString(); console.timeEnd('Buffer.from');
Buffer.from: 9.797ms

This is because atob() is intentionally unoptimized. (See rationale)

Additional context

vite-plugin-wasm has the same bug (see Menci/vite-plugin-wasm#3).

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.