Question

在将m变量添加到if条件之前，以下函数有效。但是，我注意到一个错误，当时间从上午11点到下午12点时，if else没有运行noonTime变量。我查看了我的代码并认为它与条件中没有指定的分钟有关。最初我的代码就像这样：var noonTime = (h >= 12 && h <= 17) ? true : false;。然后我将其更改为：var noonTime = (h >= 12, m > 0 && h <= 17, m == 0) ? true : false;尝试检查条件中的分钟数。

有没有人看到我在尝试检查条件下的分钟时出错了什么？

var customerName = 'Bob';
function timeNow() {
  
        var d = new Date(),
        h = ('0' + d.getHours()).slice(-2),
        m = ('0' + d.getMinutes()).slice(-2);

        // Checking time range
        var morningTime = (h >= 5 && h <= 12, m == 0) ? true : false;
        var noonTime    = (h >= 12, m > 0 && h <= 17, m == 0) ? true : false;
        var nightTime   = (h >= 17 && h <= 5)  ? true : false;
        var greeting = "";

        if (morningTime) {
            greeting = "Good Morning";
        } else if (noonTime) {
            greeting = "Good Afternoon";
        } else if (nightTime) {
            greeting = "Good Evening";
        }

        return greeting;
    }
   // var helloTime = timeNow();
    document.getElementById('dashboard-hello').innerHTML = timeNow() + ', ' + customerName + '!';
    //$('#dashboard-hello').html(helloTime + ', ' + customerName);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<div id="dashboard-hello"></div>

Answer 1

您希望将小时和分钟比较结合起来。使用括号进行这些分组可以更容易阅读。然后你只需使用你想要的范围。

＆＃13;

function getGreeting(d) {
  h = d.getHours(), // There's no reason to format these as
    m = d.getMinutes(); // strings, since you're comparing to numbers

  // Checking time range
  var morningTime = ((h >= 5 && h < 12) || (h === 12 && m == 0));
  var noonTime = ((h === 12 && m > 0) || (h > 12 && h < 17) || (h === 17 && m === 0));
  var nightTime = (h >= 17 || h <= 5)
  var greeting = "";

  if (morningTime) {
    greeting = "Good Morning";
  } else if (noonTime) {
    greeting = "Good Afternoon";
  } else if (nightTime) {
    greeting = "Good Evening";
  }

  return greeting;
}

console.log("now: " + getGreeting(new Date()));
console.log("5 am: " + getGreeting(new Date(1, 1, 1, 5, 0, 0)));
console.log("12:00pm: " + getGreeting(new Date(1, 1, 1, 12, 0, 0)));
console.log("12:01pm: " + getGreeting(new Date(1, 1, 1, 12, 1, 0)));
console.log("5:00pm: " + getGreeting(new Date(1, 1, 1, 17, 0, 0)));
console.log("5:01pm: " + getGreeting(new Date(1, 1, 1, 17, 1, 0)));
console.log("12:00am: " + getGreeting(new Date(1, 1, 1, 0, 0, 0)));

＆＃13;

我已将日期作为测试目的函数的参数。要返回它，只需删除d并将第一行代码放回原位。

Answer 2

逗号运算符将评估每个操作数，但仅返回最后一个操作数的值。在这种情况下，您可能最好使用更多的AND / OR运算符来更好地评估您尝试做的事情。

我实际上并不完全确定你想要做什么，但也许你想要：

var morningTime = ((h >= 5 && h <= 12) && m == 0) ? true : false;
var noonTime    = ((h >= 12 && m > 0) && (h <= 17 && m == 0)) ? true : false;

但也许你可以简化整个代码段，就像这样......

if (h > 5 && h <= 12) {
  return "Good Morning";
}
else if (h > 12 && h <= 17)
  return "Good Afternoon";
}
else if (h > 17 && h <= 5)
  return "Good Evening";
}

使用新的日期功能设置小时/分钟范围

2 个答案: