在 JavaScript 中切换意外标记

Question

我在以下代码中发现了意外的标记。

        switch ( hobby ) {
            case =" painting ":
                message = "Van Gogh was good at that.";
                    break;
            case =" drawing ":
                message = "Hey! Van Gogh did that too.";
                    break;
            case =" playing guitar ":
                message = "Bob Dylan played guitar.";
                    break;
            case =" sleeping in ":
                message = "My favorite hobby in the winter.";
                    break;

            default
        }

有人看到我缺少什么吗？

Answer 1

你的语法已经关闭。删除 case 后面的 =。此外，您还需要在 default 之后添加 :。

有关 switch 语句的更多信息，请参阅此处。

Answer 2

您可以利用函数语义来避免必须 break 脱离每个 case：

var message = (function(){
  switch (hobby) {
    case 'painting':        return 'Van Gogh was good at that.'
    case 'drawing':         return 'Hey! Van Gogh did that too.'
    case 'playing guitar':  return 'Bob Dylan played guitar.'
    case 'sleeping in':     return 'My favorite hobby in the winter.'
  }
}())

不过，表达此逻辑的最佳方式可能如下所示：

var messages = {
  'painting':       'Van Gogh was good at that.',
  'drawing':        'Hey! Van Gogh did that too.',
  'playing guitar': 'Bob Dylan played guitar.',
  'sleeping in':    'My favorite hobby in the winter.'
}
var message = messages[hobby]