JavaScript数组与对象相互转换的多种实现方式

const arr1 = [{
    label: '昨天',
    value: '4-09'
},{
    label: '今天',
    value: '4-10'
 
},{
    label: '明天',
     value: '4-11'
}]

// 一维数组转obj [{},{}] => {}
function Arr1ToObj(arr) {
    const obj_1 = arr.reduce((res, item, index) => (res[index] = item.value, res), {})
    console.log('一维数组转obj', obj_1);
 
    // 指定键名
    const obj_2 = arr.reduce((res, item) => (res[item.label] = item.value, res), {})
    console.log('一维数组转obj----指定键名', obj_2);
}

Arr1ToObj(arr1)

const arr2 = [['昨天','4-09'], ['今天','4-10'], ['明天','4-11']]
// 二维数组转obj [['',''],['','']] => {}
function Arr2ToObj(arr) {
    return Object.fromEntries(arr)
}
console.log('二维数组转obj', Arr2ToObj(arr2));

const obj_a = {a: 1}
const obj_b = {b: 1}
const arr3 = [['昨天','4-09'],['今天','4-10'],['明天','4-11'],[obj_a, '是一个引用类型的a'],[obj_b, '是一个引用类型的b']]
        
// 二维数组转obj by map [['',''],['','']] => {} 
function Arr2ToObjByMap(arr) {
    const map = new Map(arr)
    let obj = Object.create(null);
        
    for (let [k,v] of map) {
        obj[k] = v;
    }
    return obj;
}
console.log('二维数组转obj by map', Arr2ToObjByMap(arr3))

const obj = {
    '上午': ['上午数组值'],
    '下午': ['下午数组值'],
    '晚上': ['晚上数组值'],
}
// obj转一维数组 [{},{},{}]
function objToArr1(obj) {
    let arr = []
    Object.keys(obj).forEach(key => {
        arr.push({
            label: key,
            value: obj[key]
        })
    })
    return arr
}
console.log('obj转一维数组',objToArr1(obj));

function objToArr2(obj) {
    // 方法一
    let arr = []
    Object.keys(obj).forEach(key => {
        arr.push([key, obj[key]])
    })
    return arr
    
    // 或者 方法二
    return Object.entries(obj)
}
console.log('obj转二维数组', objToArr2(obj));

function ObjToArrByMap(obj) {
    const map = new Map(Object.entries(obj))
    console.log('map', map);
    // map转对象
    const my_map = new Map(map)
    return [...my_map]
}
console.log('obj转二维数组 by map', ObjToArrByMap(obj))