如何在 React JS 中组合具有相同日期的数组

Question

我有一个数组：data = [ {date: 4/15/2020, 9:46:07 PM, value: "abc"},         {date: 4/15/2020, 11:19:18 PM, value: "xyz"},         {date: 4/16/2020, 1:25:13 PM, value: "def"},         {date: 4/17/2020, 5:6:17 PM, value: "pqr"}       ];我必须比较日期对象并合并数组。因此，预期的输出如下所示： data = [ {date: 4/15/2020, value: ["abc", "xyz"]},         {date: 4/16/2020, value: ["def"]},         {date: 4/17/2020, value: ["pqr"]}       ];我怎样才能做到这一点？提前致谢！！

Answer 1

我的方法：

   data = [ {date: 4/15/2020, 9:46:07 PM, value: "abc"},

             {date: 4/15/2020, 11:19:18 PM, value: "xyz"},

             {date: 4/16/2020, 1:25:13 PM, value: "def"},

             {date: 4/17/2020, 5:6:17 PM, value: "pqr"}

           ];

    // Create a map for the dates

    let dataMap = {};

    data.forEach((el) => {

      let tempDate = getDateFormat(el.date);

      if (tempDate in dateMap) {

        dateMap[tempDate].value.push(el.value);

      } else {

        dateMap[tempDate] = {

          date: tempDate,

          value: [el.value],

        };

      }

    });

    data = [];

   // Fill the data

    Object.keys(dataMap).forEach((el) => data.push(dataMap[el]));

   // The format of date

    function getDateFormat(date) {

      return (

        date.getDate() + "/" + (date.getMonth() + 1) + "/" + date.getFullYear()

      );

    }

Answer 2

使用非常方便reduce

const data = [

  {date: "4/15/2020, 9:46:07 PM", value: "abc"},

  {date: "4/15/2020, 11:19:18 PM", value: "xyz"},

  {date: "4/16/2020, 1:25:13 PM", value: "def"},

  {date: "4/17/2020, 5:6:17 PM", value: "pqr"}

]

const newArray = data.reduce((acc, dt) => {

  const date = new Date(dt.date)

  const y = new Intl.DateTimeFormat('en', { year: 'numeric' }).format(date)

  const m = new Intl.DateTimeFormat('en', { month: 'numeric' }).format(date)

  const d = new Intl.DateTimeFormat('en', { day: '2-digit' }).format(date)

  

  const formatedDate = `${m}/${d}/${y}`

 

  const dateAcc = acc[formatedDate]

  if (!dateAcc) {

    acc[formatedDate] = {

      date: formatedDate,

      value: [dt.value]

    }

  } else {

    acc[formatedDate].value.push(dt.value)

  }

  return acc

}, {})

console.log(newArray)

Answer 3

const res = []

for (let i = 0; i < data.length; i++) {

  if (res.every(r => r.date !== data[i].date)) {

    res.push(data[i])

  } else {

    const index = res.findIndex(r => r.date == data[i].date)

    res[index] = {...res[index], value: [res[index].value, data[i].value]}

  }

}

console.log(res)

它的工作原理是 id 在 data.value 中有一个值