Assign keyboard shortcuts to document

keymap.js

"use strict";
function noop() { }
;
function createKeydownListener(key, modifiers = [], cb = noop) {
    const shouldHaveAlt = modifiers.includes(keymap.ALT);
    const shouldHaveCtrl = modifiers.includes(keymap.CTRL);
    const shouldHaveMeta = modifiers.includes(keymap.META);
    const shouldHaveShift = modifiers.includes(keymap.SHIFT);
    return function (event) {
        if (event.keyCode !== key.toUpperCase().charCodeAt(0))
            return;
        if (shouldHaveAlt === event.altKey &&
            shouldHaveCtrl === event.ctrlKey &&
            shouldHaveMeta === event.metaKey &&
            shouldHaveShift === event.shiftKey) {
            cb({ key: key.toUpperCase(), modifiers, event });
        }
    };
}
function keymap(key, modifiers = [], cb = noop) {
    if (key.length !== 1)
        throw new Error('key parameter should be a string of length 1');
    modifiers.forEach((modifier) => {
        if (![keymap.ALT, keymap.CTRL, keymap.META, keymap.SHIFT].includes(modifier))
            throw new Error(`modifiers elements should be one of values '${keymap.ALT}', '${keymap.CTRL}', '${keymap.META}', '${keymap.SHIFT}'`);
    });
    document.body.addEventListener('keydown', createKeydownListener(key, modifiers, cb));
}
keymap.ALT = 'alt';
keymap.CTRL = 'ctrl';
keymap.META = 'meta';
keymap.SHIFT = 'shift';
keymap('a', ['ctrl', 'shift'], (x) => {
    console.log(x);
});