查找最近的小时[javascript]

Question

我有一个这些项目的列表：

hours = ['19:30', '20:10', '20:30', '21:00', '22:00']

假设现在是20:18，我如何从列表中获取“20:10”项？我想用它来查找电视指南中当前正在播放的节目。

Answer 1

首先，我们应该以某种方式将其解析为datetime：

function parseTime(str) {
    var values = str.split(':');
    var hour = parseInt(values[0]);
    var minutes = parseInt(values[1]);
    var d = new Date();
    d.setHours(hour);
    d.setMinutes(minutes);
    return d;
}

var now = new Date();
var bestMatch = undefined;
var bestMatchDiff = undefined;

最后：

for(var i=0; i<hours.length; i++) {
    var parsedTime = parseTime(hours[i]);
    var diff = Math.abs(now - parsedTime);
    if (!bestMatchDiff || bestMatchDiff>diff) {
        bestMatch = parsedTime;
        bestMatchDiff = diff;
    }
}

bestMatch将是最接近的时间。这不是当前正在播放的节目。为此，您需要忽略尚未到来的时间：

for(var i=0; i<hours.length; i++) {
    var parsedTime = parseTime(hours[i]);
    var diff = Math.abs(now - parsedTime);
    if (now<parsedTime) {
        continue;
    }
    if (!bestMatchDiff || bestMatchDiff>diff) {
        bestMatch = parsedTime;
        bestMatchDiff = diff;
    }
}

但请记住，即使您的列表不为空，这也可能返回undefined。

Answer 2

    var hours = ['19:30', '20:10', '20:30', '21:00', '22:00']
    var diffrenceTime
    var selectedShow
    var d1 = new Date()
    var currentHH = 20
    var currentMM = 18
    d1.setHours(currentHH, currentMM, 0)
    hours.forEach(v => {
        var d2 = new Date()
        var hh = v.split(':')[0]
        var mm = v.split(':')[1]
        d2.setHours(hh, mm, 0)
        if (diffrenceTime == undefined) {
            diffrenceTime = d2 - d1
            selectedShow = v
        }
        if (d2 - d1 < 0 && d2 - d1 >= diffrenceTime) {
            diffrenceTime = d2 - d1
            selectedShow = v
        }
    })
    console.log(selectedShow)

Answer 3

要找到当前正在运行的节目(当然需要添加更多的验证)：

const currentShow = hours[
  hours.findIndex(
    (c) => new Date(`01/01/2000 ${c}`) - new Date(`01/01/2000 20:31`) >= 0
  ) - 1
];

要找到下一个节目：

const nextShow = hours.find(
  (c) => new Date(`01/01/2000 ${c}`) - new Date(`01/01/2000 20:31`) >= 0
);