Vanilla-JS Hotkeys

hotkey.js

function hotkey(hotkeys, fn) {
    hotkeys = hotkeys.split(' ');
    function test(testObj, e) {
        if (testObj.key !== e.key.toLowerCase()) return false;
        for (var key in testObj) if (key !== 'key' && testObj[key] !== e[key]) return false;
        return true;
    }
    var tests = hotkeys.map(function(hotkey){
        var testObj = {
                shiftKey: false,
                ctrlKey: false,
                altKey: false,
                metaKey: false,
                isComposing: false
            },
            keys = hotkey.toLowerCase().split('+');
        for (var i in keys) {
            switch (keys[i]) {
                case 'shift':
                case 'umschalt':
                    testObj.shiftKey = true;
                    break;
                case 'ctrl':
                case 'strg':
                    testObj.ctrlKey = true;
                    break;
                case 'alt':
                case 'option':
                    testObj.altKey = true;
                    break;
                case 'meta':
                case 'win':
                case 'super':
                case 'mod4':
                case 'command':
                case 'propeller':
                    testObj.metaKey = true;
                    break;
                case 'compose':
                    testObj.isComposing = true;
                    break;
                default:
                    if (keys[i].length !== 1) throw new Error('Unknown key: ' + keys[i].toUpperCase());
                    testObj.key = keys[i];
            }
        }
        return test.bind(null, testObj);
    });

    window.addEventListener('keydown', function(e){
        for (var i in tests) if (tests[i](e)) {
            e.hotkey = hotkeys[i];
            fn.call(this, e);
        }
    });
}