Question

我有以下json格式

{
  "timings": {
    "a": "02:57",
    "b": "05:19",
    "c": "13:22",
    "d": "17:39",
    "e": "21:26",
    "f": "21:26",
    "g": "23:40",
    "h": "02:47",
    "i": "01:22"
  }
}

使用lodash和momentjs，我如何选择值相同或在当前时间之后的对象。

我试过以下

let findTime = (times) => {
    const timeNow = moment();
    let nextEvent = null;
    lodash.find(times, function (value, key) {
        const thisTime = moment(value, 'HH:mm');
        if (thisTime.isSameOrAfter(timeNow, 'second')) {
            console.log(key + " is next");
            nextEvent = {
                'name': key,
                'time': value
            };
            return;
        }
    });
    return nextEvent;
}

问题是它不断返回项目i。我认为函数find会遍历所有条目。

我无法找到不同的解决方案。

我需要保持时间的顺序。

任何指针......？

Answer 1

不确定您到底在尝试什么。使用type mismatch的理想方法是_.find匹配（并且不会迭代下一个元素）。从谓词return true开始，return true会返回该键的值。

当你从谓词中_.find获得匹配元素时：

return true会返回第一场比赛的值

_.find会返回上一场比赛的值

_.findLast会返回第一场比赛的键

_.findKey会返回上一场比赛的键

_.findLastKey会将所有匹配项的值作为数组返回

注意：如果您想获得最近的即将到来的时间，您需要在传递给任何这些lodash函数之前对_.filter进行排序。

＆＃13;

timings

＆＃13;

let findTime = (times) => {
    const timeNow = moment();
    let nextEvent = null;
    let ret = _.find(times, function (value, key) {
        const thisTime = moment(value, 'HH:mm');
        if (thisTime.isSameOrAfter(timeNow, 'second')) {
            console.log(key + " is next");
            nextEvent = {
                'name': key,
                'time': value
            };
            return true;
        }
    });
    //return nextEvent;
    return ret; // send the return value from lodash function
}

let times = {
  "timings": {
    "a": "02:57",
    "b": "05:19",
    "c": "13:22",
    "d": "17:39",
    "e": "21:26",
    "f": "21:26",
    "g": "23:40",
    "h": "02:47",
    "i": "01:22"
  }
}
console.log('returned value:', findTime(times.timings));

＆＃13;

Answer 2

您可以使用Object.entries()将JSON作为javascript对象进行迭代，使用+运算符和.replace()将日期转换为整数。如果condition为true，则将对象的属性设置为current属性和value。

＆＃13;

const data = {
  "timings": {
    "a": "02:57",
    "b": "05:19",
    "c": "13:22",
    "d": "17:39",
    "e": "21:26",
    "f": "21:26",
    "g": "23:40",
    "h": "02:47",
    "i": "01:22"
  }
}

let res = {};

// let now = `${new Date().toJSON()}`.slice(11, 16);

let now = "21:26";

let dateToNumber = str => +str.replace(/:/, "");

for (let [key, prop] of Object.entries(data.timings)) {
  if (dateToNumber(prop) >= dateToNumber(now)) {
    // do stuff
    res[key] =  prop;
  }
}

console.log(res);

＆＃13;

Answer 3

您可以使用lodash#findKey从对象中查找特定密钥。

const findTime = times => {
  let mNow = moment();
  let name = _.findKey(times, v => moment(v, 'HH:mm').isSameOrAfter(mNow));
  var time = times[name];
  return time? { name, time }: null;
};

＆＃13;

let data = {
  "timings": {
    "a": "02:57",
    "b": "05:19",
    "c": "13:22",
    "d": "17:39",
    "e": "21:26",
    "f": "21:26",
    "g": "23:40",
    "h": "02:47",
    "i": "01:22"
  }
};

const findTime = times => {
  let mNow = moment();
  let name = _.findKey(times, v => moment(v, 'HH:mm').isSameOrAfter(mNow));
  var time = times[name];
  return time? { name, time }: null;
};

console.log(findTime(data.timings));

＆＃13;

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/moment.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>

＆＃13;

使用Lodash根据值从json获取对象

3 个答案: