Question

输入：

var data = [
  { team: 'A', score: 80, year: 2009 },
  { team: 'A', score: 180, year: 2009 },
  { team: 'A', score: 80, year: 2010 },
  { team: 'B', score: 80, year: 2009 },
  { team: 'B', score: 80, year: 2010 },
];

输出：

{
  2009: {
    A: 260,
    B: 80,
  },
  2010: {
    A: 80,
    B: 80,
  },
};

Answer 1

一种可能的解决方案是以这种方式使用Array.reduce()：

var data = [{team: 'A', score: 80, year: 2009},{team: 'A', score: 180, year: 2009}, {team: 'A', score: 80, year: 2010}, {team: 'B', score: 80, year: 2009}, {team: 'B', score: 80, year: 2010}];

// We use reduce starting with an "accumulator" equal to an empty object.
// On every iteration of "reduce", you have access to the "accumulator" and
// the current inspected element of the array (an "object"). We also use
// "destructuring" on the current inspected object.

let res = data.reduce((acc, {year, team, score}) =>
{
    // If the value hold by property "year" is not a defined property on the
    // "acc", then set it to be an empty object.
    acc[year] = acc[year] || {};

    // If the value hold by property "team" is not a defined property on
    // "acc[year]", then set it to be 0.
    acc[year][team] = acc[year][team] || 0;

    // Increment the accumulated score on "acc[year][team]". Note this will
    // be "0", thanks to previous lines, if don't previously exists.
    acc[year][team] += score;

    // Return the altered "accumulator".
    return acc;
}, {} /* This is the initial accumulator object */);

console.log(res);

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.as-console-wrapper {max-height:100% !important; top:0;}

Answer 2

var data = [{team: 'A', score: 80, year: 2009},{team: 'A', score: 180, year: 2009}, {team: 'A', score: 80, year: 2010}, {team: 'B', score: 80, year: 2009}, {team: 'B', score: 80, year: 2010}]
        var obj = {};
        for (var i = 0; i < data.length; i++) {
            if (obj[data[i].year]) {
                var a = obj[data[i].year]['A'];
                var b = obj[data[i].year]['B'];
                obj[data[i].year] = {
                    A: data[i].team === 'A' ? a + data[i].score : a,
                    B: data[i].team === 'B' ? b + data[i].score : b,
                }
            } else {
                obj[data[i].year] = {
                    A: data[i].team === 'A' ? data[i].score : 0,
                    B: data[i].team === 'B' ? data[i].score : 0,
                }
            }
        }
console.log(obj)

获取基于年份的元素总数

2 个答案: