How do I get all key states when using asm.js/emscripten/SDL?

Question

When using SDL for keyboard input only certain keys seems to work (arrows, pageup\pagedown).

This is the code I am using:

const auto sdlScanCodes = {...SDL_SCANCODE_A, SDL_SCANCODE_F1, SDL_SCANCODE_SPACE, SDL_SCANCODE_LSHIFT ...etc}

SDL_PumpEvents();
const auto sdlKeyStatesPtr = SDL_GetKeyboardState(nullptr);
for(auto sdlScanCode: sdlScanCodes) {
    const auto sdlKeyCode = SDL_SCANCODE_TO_KEYCODE(sdlScanCode);
    const bool downKeyCode = sdlKeyStatesPtr[sdlKeyCode];
    const bool downScanCode = sdlKeyStatesPtr[sdlScanCode];
}

Update: Note that downScanCode never works, and as said, downKeyCode works for some keys.

Answer 1

Worked when I used the keycodes directly, instead of converting scancodes

const auto sdlKeyCodes = {...SDLK_a, SDLK_F1, SDLK_SPACE, SDLK_LSHIFT ...etc}

SDL_PumpEvents();
const auto sdlKeyStatesPtr = SDL_GetKeyboardState(nullptr);
for(auto sdlKeyCode: sdlKeyCodes ) {
    const bool downKeyCode = sdlKeyStatesPtr[sdlKeyCode];
}

Answer 2

The array returned by SDL_GetKeyboardState should be indexed by scancodes in SDL 2.0, not keycodes as in SDL 1.2. Try doing it without the SDL_SCANCODE_TO_KEYCODE conversion.

For reference: https://wiki.libsdl.org/SDL_GetKeyboardState

Also, I should point out that SDL_SCANCODE_TO_KEYCODE is not a general-use conversion macro. It simply sets an upper bit so that certain scancodes can be unique. Use SDL_GetKeyFromScancode and SDL_GetScancodeFromKey.