您需要記住id之前見過的對象，以便可以將它們與每次循環(huán)迭代中“現(xiàn)在”查看的對象進行比較。AMap是在現(xiàn)代 JavaScript 中實現(xiàn)這一點的好方法，或者是Object.create(null)在 ES5 中創(chuàng)建的對象。
const lastSeen = new Map();
for (const entry of myArray) {
const {id, date, percentage} = entry;
const last = lastSeen.get(id);
if (last) {
if (date > last.date && percentage > last.percentage) {
// ...this entry is newer than the previous one with the matching ID
// Replace the previous one (and possibly do something with `stuff`?)
lastSeen.set(id, entry);
}
} else {
lastSeen.set(id, entry);
}
}
實例：
const myArray = [ { id: 'first', date: '2020-11-30', percentage: 10 }, { id: 'second', date: '2020-10-30', percentage: 20 }, { id: 'first', date: '2020-09-30', percentage: 30 } ];
const lastSeen = new Map()
for (const entry of myArray) {
const {id, date, percentage} = entry;
const last = lastSeen.get(id);
if (last) {
console.log(`Checking ${id} / ${date} / ${percentage}...`);
if (date > last.date && percentage > last.percentage) {
// ...this entry is newer than the previous one with the matching ID
// Replace the previous one (and possibly do something with `stuff`?)
console.log(`Replacing ${id}...`);
lastSeen.set(id, entry);
} else {
console.log(`Not replacing ${id}`);
}
} else {
console.log(`${id} is new, adding...`);
lastSeen.set(id, entry);
}
}
我沒有包含stuff上面的設置，因為不清楚let stuff = stuff;您的原始代碼的用途。id您可以找到每個最新的lastSeen或執(zhí)行上面指示的操作來處理stuff。
在 ES5 級別的代碼中（但在 2020 年即將到 2021 年，如果您需要支持過時的環(huán)境，我強烈建議編寫現(xiàn)代代碼并使用轉譯器）：
var lastSeen = Object.create(null);
for (let i = 0; i < myArray.length; ++i) {
var entry = myArray[i];
var last = lastSeen[entry.id];
if (last) {
if (entry.date > last.date && entry.percentage > last.percentage) {
// ...this entry is newer than the previous one with the matching ID
// Replace the previous one (and possibly do something with `stuff`?)
lastSeen[entry.id] = entry;
}
} else {
lastSeen[entry.id] = entry;
}
}
實例：
const myArray = [ { id: 'first', date: '2020-11-30', percentage: 10 }, { id: 'second', date: '2020-10-30', percentage: 20 }, { id: 'first', date: '2020-09-30', percentage: 30 } ];
var lastSeen = Object.create(null);
for (let i = 0; i < myArray.length; ++i) {
var entry = myArray[i];
var last = lastSeen[entry.id];
if (last) {
console.log(`Checking ${entry.id} / ${entry.date} / ${entry.percentage}...`);
if (entry.date > last.date && entry.percentage > last.percentage) {
// ...this entry is newer than the previous one with the matching ID
// Replace the previous one (and possibly do something with `stuff`?)
console.log(`Replacing ${entry.id}...`);
lastSeen[entry.id] = entry;
} else {
console.log(`Not replacing ${entry.id}`);
}
} else {
console.log(`${entry.id} is new, adding...`);
lastSeen[entry.id] = entry;
}
}
