javascript - 如何获取 javascript 中键组合的键码？

Question

    $(document).keydown(function(event) {

        doSomething(event);
        event.preventDefault();
    });

使用上面的代码，我可以获得单键的键码。但是，当我使用组合键时，我会收到第一个和第二个键的事件。例如，!(Shift + 1)、$(Shift + 4)。

如何获得组合键的键码？

Answer 1

以下是一些可以帮助您的插件：

1. https://github.com/jeresig/jquery.hotkeys
2. https://github.com/madrobby/keymaster（这个是免费的）

Answer 2

fn您可以使用基于按键和正则表达式匹配的处理回调函数触发的函数来扩展 jquerys对象

我写了一个类似的答案，在它支持单个键的正则表达式匹配之前，我只是对其进行了一些修改以支持多个键。

  $.fn.selectedKey = (function () {
      var keys = "";
      var last = "";
      var key = "";
      return function (cb, data) {
          def.call(data, {
              ctrlKey: 2, //0: musn't be pressed, 1: must be pressed, 2: both.
              altKey: 2, // "
              invert: 0, //inverts the filter
              filter: /.*/, // A Regular Expression, or a String with a Regular Expression
              preventDefault: false //Set to true to prevent Default.
          }); //Sets the default Data for the values used,

          function validate(e) {

              var exp = new RegExp(e.data.filter.replace(/\\\\(\d)/g, String.fromCharCode("$1"))); //Creates a new RegExp from a String to e.g. allow "\2" to match the keyCode 2
              var c = !! (e.data.ctrlKey ^ e.ctrlKey ^ 1 > 0); //c == true if the above stated conditions are met e.g Ctrl Key Pressed and `ctrlKey == 1` -> true
              var a = !! (e.data.altKey ^ e.altKey ^ 1 > 0); //e.g Alt Key Pressed and `altKey == 0` -> false
              //console.log(keys,exp,c,a)
              return (exp.test(keys) && (c && a)); //Returns the validation Result
          }

          function def(obj) { //a minimal helper for default values
              for (var prop in obj) {
                  this[prop] = this[prop] || obj[prop];
              }
          }
          this.keypress(data, function (e) {

              key = e.char = String.fromCharCode(e.keyCode || e.which); //Converts the pressed key to a String
              keys += ( !! ~ (keys.indexOf(key))) ? "" : key;
              key = key["to" + (e.shiftKey ? "Upper" : "Lower") + "Case"]();
              keys = keys["to" + (e.shiftKey ? "Upper" : "Lower") + "Case"](); //case handling
              if (e.data.preventDefault) e.preventDefault();

              if ((validate(e) != e.data.invert) && keys != last) {

                  cb(e);
                  last = keys;
                  //Calls the callback function if the conditions are met
              }
          });
          if (!this.data("keyupBound")) {
              this.keyup(data, function (e) {

                  key = e.char = String.fromCharCode(e.keyCode || e.which); //Converts 
                  var t = keys.toLowerCase()
                      .split("");
                  t.splice(t.indexOf(e.char), 1);
                  keys = t.join("");
                  last = keys;
              });
              this.data("keyupBound", true);
          }
      };

  })();


$("body").selectedKey(function (e) {
    console.log("All lower characters, Numbers and 'A': " + e.char);
}, {
    filter: "^[a-z]|[0-9]|A$",
    ctrlKey: 2,
    altKey: 2
});

$("body").selectedKey(function (e) {
    console.log("KeyCode 2 " + e.char); // Ctrl + b
}, {
    filter: "\\2",
    ctrlKey: 1,
    altKey: 2
});

例如，您也可以这样做filter:/.{4,5}/会触发同时按下的任何 4 到 5 个键

例如，当按下 A + S + D 时触发

$("body").selectedKey(function (e) {
    console.log("ASD has been pressed"); // Ctrl + b
}, {
    filter: "^ASD$",
    ctrlKey: 2,
    altKey: 2
});

这是一个关于JSBin的工作示例

编辑注释。修复了如果验证评估为真，则在按住键时连续触发
Edit2：修复了last变量，未正确使用...

Answer 3

您需要记住按下了哪个键。你应该监听 keyup + keydown 事件：

var keyCodesPressed = {};

$(document).keydown(function(event) {
  keyCodesPressed[event.which] = true;
  // here you should have all keys which are currently pressed:
  for (keyCode in keyCodesPressed) {
    // and you can loop over them and detect which are the ones currently pressed
  } 
});

$(document).keyup(function(event) {
  delete keyCodesPressed[event.which];
});