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法律研究對 JavaScript 中的陣列值進行分組
假設我們有一個包含某些年和週數據且類似這樣的物件陣列 −
const arr = [
{year: 2017, week: 45},
{year: 2017, week: 46},
{year: 2017, week: 47},
{year: 2017, week: 48},
{year: 2017, week: 50},
{year: 2017, week: 52},
{year: 2018, week: 1},
{year: 2018, week: 2},
{year: 2018, week: 5}
];我們需要編寫一個 JavaScript 函式，此函式接收一個這樣的陣列。該函式應該返回一個新陣列，其中所有具有 "年份" 屬性的相同值的物件都分組到一個單獨的物件中。
因此，以上陣列的輸出物件應如下所示 −
[
{ 2017 : [{
week: 45,
week: 46,
week: 47,
week: 48,
week: 50,
week: 53
},
{ 2018 : [{
week: 1,
week: 2,
week: 5
}]
]示例
程式碼如下 −
const arr = [
{year: 2017, week: 45},
{year: 2017, week: 46},
{year: 2017, week: 47},
{year: 2017, week: 48},
{year: 2017, week: 50},
{year: 2017, week: 52},
{year: 2018, week: 1},
{year: 2018, week: 2},
{year: 2018, week: 5}
];
const groupByYear = arr => {
const res = [];
const map = {};
arr.forEach(item => {
const temp = {};
if (!map[item.year]) {
map[item.year] = [];
temp[item.year] = map[item.year];
res.push(temp);
};
map[item.year].push({ value: item.week });
});
return res;
};
console.log(JSON.stringify(groupByYear(arr), undefined, 4));輸出
控制檯中的輸出 −
[
{
"2017": [
{
"value": 45
},
{
"value": 46
},
{
"value": 47
},
{
"value": 48
},
{
"value": 50
},
{
"value": 52
}
]
},
{
"2018": [
{
"value": 1
},
{
"value": 2
},
{
"value": 5
}
]
}
]
更新於： 12-Oct-2020
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