AngularJS - 同时按下多个按键 [英] AngularJS - Multiple keypress at the same time

问题描述

我有以下 $broadcast 来捕捉 Angular 中的按键:

I have the following $broadcast to catch keypresses in Angular:

$document.bind('keypress', function(event) {
    var key = event.which;
    $rootScope.$broadcast('keypress', event);
    $rootScope.$broadcast('keypress:' + key, event);
});

我用 $on

但是，我想检测两个键何时被同时按下，比如 enter 和 s 被同时按下(不是一个一个的组合由另一个).

However, I want to detect when two keys are pressed at the same time, say enter and s are pressed at the same time (not a combination one one followed by another).

这样做的最佳方法是什么?

What is the best way of doing this?

编辑

我的想法是:

var keys = [];
$document.bind('keydown', function(event) {
    keys[event.which] = true;
});
$document.bind('keyup', function(event) {
    delete keys[event.which];
});

$document.bind('keypress', function(event) {
    var key = event.which;
    var keysPressed = [];
    angular.forEach(keys, function(value, key) {
        keysPressed += 'keypress:' + key;
    });
    $rootScope.$broadcast('keypress', event);
    $rootScope.$broadcast(keysPressed, event);
});

因此，如果我有多个按键，那么我会创建正确的 $broadcast.然而，问题变成了现在的顺序很重要(即，如果我按 a 然后按 enter，那么 $broadcast 是 keypress:58keypress:13 如果我按其他方式，我得到 keypress:13keypress:58)

So if I have multiple keypresses, then I create the correct $broadcast. The problem, however, becomes that the order matters now (i.e., if I press a then enter, then the $broadcast is keypress:58keypress:13 and if I press the other way, I get keypress:13keypress:58)

推荐答案

在我看来，广播使用的太多了.相反，也许使用自定义指令?这是一个用户按下 Shift+Tab 的例子，它会触发一个这样的事件:

Broadcast is used way too much in my opinion. Instead, maybe use a custom directive? This is an example of user pressing down Shift+Tab and it fires an event like so:

<input on-shift-tab="prevStep($event,'email')" />

app.directive('onShiftTab', function() {
return function(scope, element, attrs) {
    var map = {9: false, 16: false};

    element.on("keydown", function(event) {
        if (event.which in map) {
            map[event.which] = true;
            if (map[9] && map[16]) {
                scope.$apply(function(){
                    scope.$eval(attrs.onShiftTab, {'$event': event});
                });
                event.preventDefault();
            }
        }
    });
    element.on("keyup", function(event) {
        if (event.which in map) {
            map[event.keyCode] = false;
        }
    });
};
})

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