單擊按鈕后，fruitData 數組中的數據將添加到另一個名為“history”的數組中。我希望每當屬性“kultivar”、“blokNommer”和“year”與從fruitData 添加的對象匹配時，歷史記錄中的屬性“bins”就會更新。（如果有匹配，則 bins 屬性內的數字需要相加）例如這個：[{datum: "2020-04-08", kultivar: "bc", ha: "5", blokNommer: "1", bins: "20", year: "2020"}, {datum: "2020-04-08", kultivar: "bc", ha: "5", blokNommer: "1", bins: "20", year: "2020"}]應等于此（垃圾箱：40）：[ {datum: "2020-04-08", kultivar: "bc", ha: "5", blokNommer: "1", bins: "40", year: "2020"}]我的代碼：let fruitData = [{ datum: "2020-04-08", kultivar: "bc", ha: "5", blokNommer: "1", bins: "20", year: "2020" }, { datum: "2020-09-18", kultivar: "wb", ha: "5", blokNommer: "1", bins: "5", year: "2020" }, { datum: "2020-03-09", kultivar: "bc", ha: "5", blokNommer: "1", bins: "20", year: "2020" }, { datum: "2020-04-08", kultivar: "bc", ha: "5", blokNommer: "1", bins: "20", year: "2020" }]historyButton.addEventListener('click', () => { addToHistory(fruitData)})function addToHistory(elements) { for (let elem in elements) { history = [...history, elements[elem]]; } sortHistory()}function sortHistory() { let newHistory = []; history.forEach(function(item, index) { if (newHistory.length === 0) { newHistory.push(item) } else { newHistory.forEach(function(itm, idx) { if (item.year === itm.year && item.kultivar === itm.kultivar && item.blokNommer === itm.blokNommer) { item.bins = item.bins + itm.bins } else { newHistory.push(item) } }) } }) console.log(newHistory)}這沒有給出我正在尋找的輸出。也嘗試過減少方法但沒有運氣。將不勝感激任何幫助！
3 回答
海綿寶寶撒
TA貢獻1809條經驗 獲得超8個贊
您需要迭代原始數組，并使用檢索數組中與 , 匹配的find()現有項目，以便訪問和更新它。historykultivarblokNommeryearbins
注意：在示例中將binsby轉換為其字符串也很重要，然后將其轉換回.Number()string
const arr = [
{datum: "2020-04-08", kultivar: "bc", ha: "5", blokNommer: "1", bins: "20", year: "2020"},
{datum: "2020-09-18", kultivar: "wb", ha: "5", blokNommer: "1", bins: "5", year: "2020"},
{datum: "2020-03-09", kultivar: "bc", ha: "5", blokNommer: "1", bins: "20", year: "2020"},
{datum: "2020-04-08", kultivar: "bc", ha: "5", blokNommer: "1", bins: "20", year: "2020"}
]
const history = [];
arr.forEach(item => {
const found = history.find(({ kultivar, blokNommer, year }) =>
kultivar === item.kultivar && blokNommer === item.blokNommer && year === item.year)
if(found) {
found.bins = (Number(found.bins) + Number(item.bins)).toString();
} else {
history.push(item);
}
});
console.log(history);
嚕嚕噠
TA貢獻1784條經驗 獲得超7個贊
如果您的fruitData數組不是很大，您可以嘗試使用迭代元素并搜索indexOf整個數組，將其轉換為字符串JSON.stringify
但如果數組很大，則代碼不是最佳的
const fruitData = [
{datum: "2020-04-08", kultivar: "bc", ha: "5", blokNommer: "1", bins: "20", year: "2020"},
{datum: "2020-09-18", kultivar: "wb", ha: "5", blokNommer: "1", bins: "5", year: "2020"},
{datum: "2020-03-09", kultivar: "bc", ha: "5", blokNommer: "1", bins: "20", year: "2020"},
{datum: "2020-04-08", kultivar: "bc", ha: "5", blokNommer: "1", bins: "20", year: "2020"}]
const sortHistory = (myArray) => Object.keys(myArray).reduce((accum, item) => {
const currItem = JSON.stringify(myArray[item])
const allArr = JSON.stringify(accum)
return (allArr.indexOf(currItem) >= 0) ? accum : accum.concat(myArray[item])
}, [])
console.log(sortHistory(fruitData))
繁星coding
TA貢獻1797條經驗 獲得超4個贊
您的實施的問題是您正在更改itm.bins. Array.forEach 在遍歷每個元素時創建每個元素的副本，因此您更改的任何值都itm不會反映在實際數組中。idx因此，如果您想更改實際元素，則會向您提供。
另外，您用于+添加字符串，而不是整數。您需要先將其轉換為整數才能獲得所需的結果。
最終代碼應該是：
function sortHistory(){
let newHistory = [];
history.forEach(function(item, index){
if(newHistory.length === 0){
newHistory.push(item)
} else{
newHistory.forEach(function(itm, idx){
if(item.year === itm.year && item.kultivar === itm.kultivar && item.blokNommer ===
itm.blokNommer){
newHistory[idx].bins = parseInt(item.bins) + parseInt(itm.bins);
}else{
newHistory.push(item)
}
})
}
})
console.log(newHistory);
history = newHistory;}
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