javascript - 如何检测单个控件的按键事件而不是组合键？

Question

很容易检测控制键事件

document.addEventListener('keyup', handler, false);

...

function handler(e) {
    var key = e.which || e.keyCode;

    if (key == 17) { // Control key
        ...
    }
}

问题是任何组合键如control-c和control-v也会触发事件，似乎事件处理程序无法区分单个 control 和 control-c control kbd>.

我想要的是只允许按下并释放单个键，而不是组合键来触发事件。

Answer 1

这个怎么样:

var controlConsidered = false;

function ctrlPressed() {
  console.log("Control was pressed.");
}

function keydownhandler(e) {
  var key = e.which || e.keyCode;
  controlConsidered = (key == 17);
}

function keyuphandler(e) {
  var key = e.which || e.keyCode;
  if (key == 17 && controlConsidered) {
    ctrlPressed();
  }
}

document.addEventListener('keydown', keydownhandler, false);
document.addEventListener('keyup', keyuphandler, false);