使用Lodash根据值从JSON获取对象

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，如何选择值相同或在当前时间之后的对象。

我尝试了以下

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;
}

问题是无论如何我都会不断退货。 我发现该函数可以遍历所有条目。

我找不到其他解决方案。

我需要保持时代的秩序。

任何指针...？

Answer 1

不知道您到底在尝试什么。 使用_.find的理想方法是为匹配return true （并且不会迭代下一个元素）。 当您从谓词中return true ， _.find将返回该键的值。

当您从匹配元素的谓词return true ：

_.find返回您第一次匹配的值

_.findLast返回最后匹配的值

_.findKey返回你的第一场比赛的关键

_.findLastKey返回最后匹配的键

_.filter以数组的_.filter返回所有匹配项的值

注意：如果要获取最近的即将到来的时间，则需要在传递给这些lodash函数中的任何一个之前对timings进行排序。

 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)); 

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

Answer 2

您可以使用Object.entries()将JSON迭代为javascript对象，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当前属性和值。

 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); 

Answer 3

您可以使用lodash#findKey从对象中查找特定的键。

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;
};

 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)); 

 <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>