[dandotway]

Big Endian POWER isn't bug-for-bug compatible with buggy Javascript usage of typed arrays that assumes little endianness, and thus browsers/nodejs/deno on POWER will be exposed to bugs that don't affect little endian x86-64/ARM.

After so many years of endianness bugs in C/C++ code, it's perplexing that the web standards committee voted to put typed arrays in Javascript in such a way that exposes platform byte order to Javascript programmers who can't generally be expected to have low-level C/C++/ASM experience with memory layout issues:

  function endianness () {
    let u32arr = new Uint32Array([0x11223344]);
    let u8arr = new Uint8Array(u32arr.buffer);
    if (u8arr[0] === 0x44)
        return 'Little Endian';
    else if (u8arr[0] === 0x11)
        return 'Big Endian';
    else
        return 'WTF (What a Terrible Failure)';
  }

EDIT: my old Power Mac was big endian, but I just read POWER has an endianness toggle. So in little endian mode it ought run endian-buggy JS with bug-for-bug compatibility.

[classichasclass]

Spoiler alert: it does (typing this in Firefox 96 on a little-endian POWER9). In TenFourFox, which ran exclusively big, we had code to byteswap typed arrays to make them look little-endian to scripts. This partially worked (enough for many `asm.js` scripts to run).