JS面试题求解 about frontend-interview HOT 39 OPEN

        var data = {
            rows: [
                ["Lisa", 16, "Female", "2000-12-01"],
                ["Bob", 22, "Male", "1996-01-21"]
            ],
            metaData: [{
                name: "name",
                note: ''
            }, {
                name: "age",
                note: ''
            }, {
                name: "gender",
                note: ''
            }, {
                name: "birthday",
                note: ''
            }]
        }

        var result = data.rows.reduce(function(prev1, cur1) {
            prev1.push(data.metaData.reduce(function(prev, cur, index) {
                prev[cur.name] = cur1[index];
                return prev;
            }, {}))
            return prev1;
        }, []);

        console.log(result);
        console.log(result[0]);
        console.log(result[1]);

测试结果：
[Object, Object]
Object {name: "Lisa", age: 16, gender: "Female", birthday: "2000-12-01"}
Object {name: "Bob", age: 22, gender: "Male", birthday: "1996-01-21"}

let  a={
rows: [
["Lisa", 16, "Female", "2000-12-01"],
["Bob", 22, "Male", "1996-01-21"]
],
metaData: [
{name: "name", note: ''},
{name: "age", note: ''},
{name: "gender", note: ''},
{name: "birthday", note: ''}
]
};
let rows=a.rows;
let metaData=a.metaData;
let props=[];
let result=[];
for(let i=0;i<metaData.length;i++)
  {
    props.push(metaData[i].name)
  }
for(let j=0;j<rows.length;j++)
  {
   let  ob=new Object 
    for(let k=0;k<props.length;k++)
      { 
        var name=props[k];
        ob[name]=rows[j][k];
      }
    result.push(ob);
  }
console.log(result);  

function formatData(rows,names){
        var newData = [];
        for(var i = 0,rl = rows.length; i < rl; i++){
            var newObj = {};
            for(var j = 0,nl = names.length; j < nl; j++){
                newObj[names[j].name] = rows[i][j];
            }
            newData.push(newObj);
        }

        return newData;
    }

moment('2016-12-30', 'YYYY-MM-DD').format('W')

const map = a.reduce((acc, curr, index) => {
  acc[curr.id] = index;
  return acc;
}, {});

var database = {
	rows: [
	["Lisa", 16, "Female", "2000-12-01"],
	["Bob", 22, "Male", "1996-01-21"]
	],
	metaData: [
	{name: "name", note: ''},
	{name: "age", note: ''},
	{name: "gender", note: ''},
	{name: "birthday", note: ''}
	]
}

function index (data) {
	let rows = data.rows;
	let metaData = data.metaData;
	let narr={};
	for(var j=0; j<rows.length;j++){
		for(var  i = 0; i<metaData.length; i++){
			var arr = [];
			narr[metaData[i].name] = rows[j][i];
			arr.push(narr);
			
		}
		console.log(arr)
	}
	
	
}

let a = {
    rows: [
        ['Lisa', 16, 'Female', '2000-12-01'],
        ['Bob', 22, 'Male', '1996-01-21']
    ],
    metaData: [
        { name: 'name', note: '' },
        { name: 'age', note: '' },
        { name: 'gender', note: '' },
        { name: 'birthday', note: '' }
    ]
};

let rows = a.rows, metaData = a.metaData, result = [];

for (let i = 0, len = rows.length; i < len; i++) {
    let _stack = result[i] = {};
    for (let k = 0; k < rows[i].length; k++) {
        _stack[ metaData[k].name ] = rows[i][k];
    }
}
console.log(result);

b = [
	{id: 10001, gender: "Female"},
	{id: 10002, name: "Bob King", birthday: "1996-01-22"},
	{id: 10005, name: "Tom", birthday: "2000-01-01"},
];
b.forEach(function (itemB,indexB,arrB) {
	a.forEach(function (itemA,indexA,arrA) {
		if(itemA.id == itemB.id){
			for(var key in itemB){
				itemA[key] = itemB[key];
			}
		} else{
			var noHave = true;
			for(var i=0;i< a.length;i++){
				if(a[i].id == itemB.id){
					noHave = false;
				}
			}
				if(noHave){
					a.push(itemB);
				}
		}
	})
})

    var data = {
        rows: [
            ["Lisa", 16, "Female", "2000-12-01"],
            ["Bob", 22, "Male", "1996-01-21"]
        ],
        metaData: [
            {name: "name", note: ''},
            {name: "age", note: ''},
            {name: "gender", note: ''},
            {name: "birthday", note: ''}
        ]
    };
    var rows = data.rows;
    var metaData = data.metaData;
    var sbData = {};
    var allData = [];
    for(var i=0; i<rows.length; i++){
        sbData = {};
        for(var j=0; j<metaData.length; j++){
            sbData[metaData[j].name] = rows[i][j];
        }
        allData.push(sbData);
    }
    console.log(allData);

var a = [
    {id: 10001, name: "Lisa", age: 16},
    {id: 10002, name: "Bob", age: 22},
    {id: 10003, name: "Alice", age: 20},
];
var b = [
    {id: 10001, gender: "Female"},
    {id: 10002, name: "Bob King", birthday: "1996-01-22"},
    {id: 10005, name: "Tom", birthday: "2000-01-01"},
];
b:for(var i=0; i<b.length; i++){
    for(var j=0; j<a.length; j++){
        if(a[j].id == b[i].id){
            for(var key in b[i]){
                a[j][key] = b[i][key];
            }
            continue b;
        }
    }
    a.push(b[i]);
}
console.log(a);

var arr=[];
var meta=obj.metaData;
for(var i=0;i<obj.rows.length;i++){
    var o=new Object();
    console.log(o);
    for(var n=0;n<meta.length;n++){
        console.log(meta[n].name);
        var na=meta[n].name;
        o[na]=obj.rows[i][n];
    }
    arr.push(o);
}
console.log(arr);

var arr = [];
data.rows.forEach((currentValue, index) => {
	var obj = {};
	currentValue.forEach((currentValueItem, indexItem) => {
		obj[data.metaData[indexItem]['name']] = currentValueItem;
	})
	arr.push(obj);
})
console.log(arr);

var arr_id = [];
var arr = a.concat(b);
var arr_result = [];
for (var i = 0; i < arr.length; i++) {
	arr_id.push(arr[i]['id']);
};
arr_id = [...new Set(arr_id)];
for (var i = 0; i < arr_id.length; i++) {
	var obj = {};
	for (var j = 0; j < arr.length; j++) {
		if (arr_id[i] == arr[j]['id']) {
			obj = Object.assign(obj, arr[j]);
	        }
	};
	arr_result.push(obj);
};
console.log(arr_result);

var data = {
        rows: [
            ["Lisa", 16, "Female", "2000-12-01"],
            ["Bob", 22, "Male", "1996-01-21"]
        ],
        metaData: [
            {name: "name", note: ''},
            {name: "age", note: ''},
            {name: "gender", note: ''},
            {name: "birthday", note: ''}
        ]
    };

    function func(data){
        let obj = {};
        let results = [];
        let arr = data.metaData.map(e=>e.name);
        for(let i = 0;i<data.rows.length;i++) {
            for(let j = 0;j<data.metaData.length;j++){
                obj[arr[j]]=data.rows[i][j];
            }

            results.push(JSON.parse(JSON.stringify(obj)))
        }
        console.log(results)
    }
    func(data);

Weekly('09, 21, 2005')
function Weekly(a)  {
    // 将输入的时间转换成标准格式
    a = new Date(a)
    // 计算输入的时间在几月，在第几周
    let month = a.getMonth() + 1
    let week = a.getDate()/7 | 1
    // 只要本月前七天都不是周一，那本月1号往后的就计入本月，否则就计入上一月的第五周
    if(a.getDate() < 7) { // 前七天
        if (a.getDay() !== 1) {     // 第几周都不为周一
            month = a.getMonth()
            week = 5
        }
    }
    console.log(month,week)
}

const formatData = (oriData)=>{
	let resultArr = [];
	let rows = oriData.rows;
	let metaData = oriData.metaData;
	for(let i=0;i<rows.length;i++){
		let temp = {};
		rows[i].forEach((value,index,array)=>{
			temp[metaData[index].name] = value
		});
		resultArr.push(temp);
	}
	console.log(resultArr);
};

    const updateData = (mainData,subData)=>{
        for(let i=0;i<b.length;i++){
            let hasData = false;
            for(let j=0;j<a.length;j++){
                if(subData[i].id === mainData[j].id){
                    hasData = true;
                    console.log(mainData[j].id)
                    mainData[j] = Object.assign(mainData[j],subData[i])
                }
            }; 
            if(!hasData){
                mainData.push(subData[i]);
            }
        }
        return mainData;
    };

//二、写一个函数，判断给定的日期是几月的第几周，当月1日属于上一月的，该周计入上一月。   例如：
// 1）输入日期2016-02-01，返回结果为2-1，表示2016年2月1日属于2月的第一周；
// 2）输入日期2016-09-01，返回结果为8-5，表示2016年9月1日属于8月的第五周。

function whichDay(time){
   var time = new Date(time);
   var date = time.getDate();
   var month= 1;
   var week= 0;
   var end ;
   var weekday = time.getDay();
   if(weekday==0){
   	weekday = 7;
   	end = "日";
   }else{
   	end = weekday
   };
   var remain = date%7
   var year = time.getFullYear();
   if(date>=7){
   	if(remain<weekday){
   		week = Math.floor(date/7)
   		
   	}else{
   		week = Math.ceil(date/7)
   		
   	};
   	month = time.getMonth()+1;
   }else if(date<7){
   	if(remain<weekday){
   		week = Math.floor(date/7)+5;
   		month = time.getMonth();
   	}else{
   		week = Math.ceil(date/7);
   		month = time.getMonth()+1;
   	};
   };
   console.log(year+"第"+month+"月"+"第"+week+"周"+"星期"+end);

};
whichDay("2016-02-01");
whichDay("2016-09-01");

function getDays(year, month) {

    var days;
    //当月份为二月时，根据闰年还是非闰年判断天数
    if (month == 2) {
        days = year % 4 == 0 ? 29 : 28;

    } else if (!(month+'').replace(/(1|3|5|7|8|10|12)/, '')) {
        //月份为：1,3,5,7,8,10,12 时，为大月.则天数为31；
        days = 31;
    } else {
        //其他月份，天数为：30.
        days = 30;

    }
    return days;
}
function getWeek(date){
    let currDate = new Date(date.toString().replace('-', ','));
    let week = currDate.getDay()==0?7:currDate.getDay();
    let day = currDate.getDate();
    let month = currDate.getMonth()+1;
    let year = currDate.getFullYear();
    let preMonthDays = month>1?getDays(year, month-1):getDays(year-1, 12);
    if(day<8){
        if(week<=day){
            return `${year}年${month}月${day}日:${month}-1`
        }else{
            month = month>1?(month-1):12;
            return `${year}年${month+1}月${day}日:${(month)}-${(Math.floor((preMonthDays-week+1)/7)+1)}`;
        }
    }else{
        return `${year}年${month}月${day}日:${month}-${Math.floor((day-week+1)/7)+1}`
    }
}

function convert (source) {
  return source.rows.map(row => {
    return row.reduce((acc, item, i) => {
      debugger
      acc[source.metaData[i].name] = item
      return acc
    }, {})
  })
}

function arrToMap (arr, key='id') {
  return arr.reduce((acc, item) => {
    acc[item[key]] = item
    return acc
  }, {})
}

function mapToArr (obj) {
  return Object.keys(obj).map(k => obj[k])
}

function merge (a, b) {
  const aMap = arrToMap(a)
  b.forEach(item => {
    if (!aMap[item.id]) aMap[item.id] = {}
    return Object.assign(aMap[item.id] , item)
  })
  return mapToArr(aMap)
}