javascript - JS : Reduce array to nested objects

Question

所以我有这个数组

var mapped = [[2016, "October", "Monday", {object}], [2017, "January", "Friday", {object}], [2017, "January", "Wednesday", {object}], [2017, "October", "Monday", {object}]]

我想要完成的是这样的:

[{
    "2016": [{
        "October": [{
            "Monday": [{object}]
        }]
    }],
}, {
    "2017": [{
        "January": [{
            "Friday": [{object}]
        }, {
            "Wednesday": [{object}]
        }]
    }, {
        "October": [{
            "Monday": [{object}]
        }]
    }]
}]

我已经搜索了很长时间，但找不到解决方案。通过使用 reduce，我得到了这样的结果:

[
    2016: [{
        "month": "October"
    }]
],
[
    2017: [{
        "month": "January"
    },
    {
        "month": "January"
    },
    {
        "month": "September"
    }]
]

所以看起来我很感兴趣，但还很遥远......这就是我正在做的:

mapped.reduce((years, array) => {

                    years[array[0]] = years[array[0]] || [];

                    years[array[0]].push({
                        month: array[1]
                    })

                    return years;

                }, [])

Answer 1

不完全是你指定的，但我觉得下面的脚本输出一种最有用的格式——它只在最深的层次上产生数组:

const  mapped = [[2016, "October", "Monday", { a: 1 }], [2017, "January", "Friday", { a: 1 }], [2017, "January", "Wednesday", { a: 1 }], [2017, "October", "Monday", { a: 1 }]];
   
const result = mapped.reduce( (acc, [year, month, day, object]) => {
    let curr = acc[year] = acc[year] || {};
    curr = curr[month] = curr[month] || {};
    curr = curr[day] = curr[day] || [];
    curr.push(object);
    return acc;
}, {});

console.log(result);
   

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

用数组环绕

如果你真的需要包装数组，你可以对之前的结果应用一个额外的递归函数:

const  mapped = [[2016, "October", "Monday", { a: 1 }], [2017, "January", "Friday", { a: 1 }], [2017, "January", "Wednesday", { a: 1 }], [2017, "October", "Monday", { a: 1 }]];
   
const result = mapped.reduce( (acc, [year, month, day, object]) => {
    let curr = acc[year] = acc[year] || {};
    curr = curr[month] = curr[month] || {};
    curr = curr[day] = curr[day] || [];
    curr.push(object);
    return acc;
}, {});

function wrapInArrays(data) {
    return Array.isArray(data) ? data 
        : Object.entries(data).map ( ([key, value]) => {
            return { [key]: wrapInArrays(value) };
        });
}

const wrapped = wrapInArrays(result);
console.log(wrapped);

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