Question

我有一个场景，这个功能齐全的按钮名为btnRemove，

player.onTracksChanged_ = function(event) {
  // Update the track lists.
  var lists = {
    video: document.getElementById('videoTracks'),
    audio: document.getElementById('audiotrackButton'),
    text: document.getElementById('captionButton')
  };
  var formatters = {
    video: function(track) {
      return track.width + 'x' + track.height + ', ' +
             track.bandwidth + ' bits/s';
    },
    audio: function(track) {
      return 'language: ' + track.language + ', ' +
         track.bandwidth + ' bits/s';
    },
    text: function(track) {
      return 'language: ' + track.language + ' ' +
         '(' + track.kind + ')';
    }
  };

  // Clear the old track lists.
  Object.keys(lists).forEach(function(type) {
    var list = lists[type];
    while (list.firstChild) {
      list.removeChild(list.firstChild);
    }
  });

  // Populate with the new tracks.
  var tracks = player.getTracks();
  tracks.sort(function(t1, t2) {
    // Sort by language, then by bandwidth.
    if (t1.language) {
      var ret = t1.language.localeCompare(t2.language);
      if (ret) return ret;
    }
    return t1.bandwidth - t2.bandwidth;
  });
  tracks.forEach(function(track) {
    var list = lists[track.type];
    var option = document.createElement('option');
    option.textContent = formatters[track.type](track);
    option.track = track;
    option.value = track.id;
    option.selected = track.active;
    list.appendChild(option);
  });
};

现在我想这样做，以便当按下 DELETE -key时，触发btnRemove按钮并删除焦点中的项目/所选元素。

以下是代码：

            var mediaTracks = player.getTracks();               
            if (mediaTracks.length >= 2) {
                console.log('there are more than 2 tracks');
            } else {
                console.log('there are less than 2 tracks');
            };

当我运行它时，每当我按 DELETE 时，控制台都会输出 DELETE ，但它不会输出“ ATTEMPT ---- “在那之后。

我认为没有任何理由不应该触发

是什么？

Answer 1

您正在尝试将KeyCode与String进行比较。将条件更改为 -

if (KeyCode.DELETE == event.getCode()) { ... }

你在第一个println看到的是KeyCode的toString，它显然返回了它的名字。

条件已满足，但if语句不会触发？

1 个答案: