如何在 JavaScript 中过滤和映射数组

Question

原始数组中有几个对象，每个对象都有三个属性（时间戳、姓名和年龄）。

如果一行中的多个时间戳相隔 15 分钟，它们将被分组到同一个对象中。之后，将添加一个名为 end 的新属性，它将是该组最后一个元素的时间戳值加上 15 分钟。

如果一行中没有多个元素相差 15 分钟，则最后属性将时间戳加上 15 分钟作为值。

这是我当前的代码：

const data = [
    {
        timestamp: '2021-11-23T14:15:00+0000',
        name: 'John',
        age: 25,
    },
    {
        timestamp: '2021-11-23T14:30:00+0000',
        name: 'John',
        age: 25,
    },
    {
        timestamp: '2021-11-23T14:45:00+0000',
        name: 'John',
        age: 25,
    },
    {
        timestamp: '2021-11-23T15:45:00+0000',
        name: 'John',
        age: 25,
    },
    {
        timestamp: '2021-11-23T14:15:00+0000',
        name: 'Anne',
        age: 32,
    },
    {
        timestamp: '2021-11-23T14:30:00+0000',
        name: 'Anne',
        age: 32,
    },
    {
        timestamp: '2021-11-23T14:45:00+0000',
        name: 'Anne',
        age: 32,
    },
    {
        timestamp: '2021-11-23T15:45:00+0000',
        name: 'Anne',
        age: 32,
    },
]

const newArray = data.reduce((accumulator, current) => {
    const end = new Date(Date.parse(current.timestamp) + 15 * 60 * 1000)
    if (accumulator.length === 0) {
        accumulator.push({
            ...current,
            end,
        })
    } else {
        const last = accumulator[accumulator.length - 1]
        if (last.name === current.name && last.age === current.age) {
            last.end = end
        } else {
            accumulator.push({
                ...current,
                end,
            })
        }
    }
    return accumulator
}, [])

console.log(newArray)

但是我的代码的最终结果并不是我想要的。我希望我的结果是这样的：

[
    {
        timestamp: '2021-11-23T14:15:00+0000',
        name: 'John',
        age: 25,
        end: '2021-11-23T15:00:00+0000'
    },
    {
        timestamp: '2021-11-23T15:45:00+0000',
        name: 'John',
        age: 25,
        end: '2021-11-23T16:00:00+0000'
    },
    {
        timestamp: '2021-11-23T14:15:00+0000',
        name: 'Anne',
        age: 32,
        end: '2021-11-23T15:00:00+0000'
    },
    {
        timestamp: '2021-11-23T15:45:00+0000',
        name: 'Anne',
        age: 32,
        end: '2021-11-23T16:00:00+0000'
    }
]

Answer 1

您可以像在您自己的代码中一样使用Array.reduce()来获得所需的结果，但我们可以稍作更改以更新累加器数组中的lastItem if

名称相同（lastItem.name === 名称）
日期在 15 分钟内

如果不满足此条件，我们只需添加到累加器数组。

const data = [ { timestamp: '2021-11-23T14:15:00+0000', name: 'John', age: 25, }, { timestamp: '2021-11-23T14:30:00+0000', name: 'John', age: 25, }, { timestamp: '2021-11-23T14:45:00+0000', name: 'John', age: 25, }, { timestamp: '2021-11-23T15:45:00+0000', name: 'John', age: 25, }, { timestamp: '2021-11-23T14:15:00+0000', name: 'Anne', age: 32, }, { timestamp: '2021-11-23T14:30:00+0000', name: 'Anne', age: 32, }, { timestamp: '2021-11-23T14:45:00+0000', name: 'Anne', age: 32, }, { timestamp: '2021-11-23T15:45:00+0000', name: 'Anne', age: 32, }, ] 
    
const result = data.reduce((acc, { timestamp, name, age }) => { 
    let lastItem = acc[acc.length - 1];
    let end = new Date(Date.parse(timestamp) + 15*60*1000);
    
    // If the current row matches just update the end time
    if (lastItem && lastItem.name === name && (Date.parse(lastItem.end) - Date.parse(timestamp) >= 0)) { 
        lastItem.end = end;
    } else {
        acc.push({ timestamp, name, age, end });
    } 
    return acc;
}, [])

console.log(result)

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Answer 2

您可以搜索最后一个间隔，如果找到则更新 end。否则添加一个新对象。

const data = [{ timestamp: '2021-11-23T14:15:00+0000', name: 'John', age: 25 }, { timestamp: '2021-11-23T14:30:00+0000', name: 'John', age: 25 }, { timestamp: '2021-11-23T14:45:00+0000', name: 'John', age: 25 }, { timestamp: '2021-11-23T15:45:00+0000', name: 'John', age: 25 }, { timestamp: '2021-11-23T14:15:00+0000', name: 'Anne', age: 32 }, { timestamp: '2021-11-23T14:30:00+0000', name: 'Anne', age: 32 }, { timestamp: '2021-11-23T14:45:00+0000', name: 'Anne', age: 32 }, { timestamp: '2021-11-23T15:45:00+0000', name: 'Anne', age: 32 }]

const newArray = data.reduce((accumulator, current) => {
    const
        end = new Date(Date.parse(current.timestamp) + 15 * 60 * 1000).toISOString(),
        item = accumulator.find(o =>
            o.name === current.name &&
            o.end === new Date(current.timestamp).toISOString()
        );
    
    if (item) item.end = end;
    else accumulator.push({ ...current, end });

    return accumulator;
}, [])

console.log(newArray);

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