The salary is too low to resign, so it’s hard to do the interview.
I’ve been interviewing for many times, so I’ll take a quick look at one question every day.
After days and months multiplying, I will organize some of my front end questions into a daily question, then push them to the official account, and only need a few minutes a day to do a question. After accumulating, you will get a better job when you change your job.offer. Today’s article is to sort out the better questions in the recent daily question and some answers shared by fans, and share them with more friends. I hope it can help you. At the same time, we should pay attention to the official account [front end play], and push the daily question on time every day at eight forty every morning.
Topic 1
subject
Now there is a list of pocket money given by my wife every month, but for some reasons, some months have no pocket money, as shown in the following data
//Pocket money for January, February and may
{1:200, 2:140, 5:400}Please convert the above data format to[200, 140, null, null, 400, null, null, null, null, null, null, null]Where the length of the array is12, corresponding to 12 months, please complete the following code
const obj = { 1: 200, 2: 140, 5: 400 };
function translate(obj) {
//Please add code here
}
//Output [200, 140, null, null, 400, null, null, null, null, null, null, null, null]
console.log(translate(obj));answer
There are many answers to this question. The following lists the answers contributed by several group friends for your reference
Answer one
const obj = { 1: 200, 2: 140, 5: 400 };
function translate(obj) {
return Array.from({ length: 12 }).map((_, index) => obj[index + 1] || null);
}
//Output [200, 140, null, null, 400, null, null, null, null, null, null, null, null]
console.log(translate(obj));Answer two
const obj = { 1: 200, 2: 140, 5: 400 };
function translate(obj) {
return Object.assign(Array(13).fill(null), obj).slice(1);
}
//Output [200, 140, null, null, 400, null, null, null, null, null, null, null, null]
console.log(translate(obj));Answer three
const obj = { 1: 200, 2: 140, 5: 400 };
function translate(obj) {
//Please add code here
let result = Array(12).fill(null)
Object.entries(obj).forEach(([key, value]) => {
result[key - 1] = value;
});
return result;
}
//Output [200, 140, null, null, 400, null, null, null, null, null, null, null, null]
console.log(translate(obj));Topic 2
subject
Please output1reach400The number of 1 contained in all numbers between, such as numbers1It contains a1, number11There are two1, number20Not included in1, number1reach21The Chinese Communist Party includes13individual1。
function getCount() {
}
//Output 180
console.log(getCount())answer
Answer one
The answer is classic, and the performance is very good
const sum1s = num => {
let numstr
if (!num) return 0
if (typeof num === 'string') numstr = num
else numstr = String(num)
if (Number(numstr) === 0) return 0
const curr =
numstr[0] > 1
? 10 ** (numstr.length - 1) +
numstr[0] * (numstr.length - 1) * 10 ** (numstr.length - 2)
: sum1s(10 ** (numstr.length - 1) - 1) + 1
return curr + sum1s(numstr.substr(1))
}
//Output 180
console.log(sum1s(400))Answer two
This uses regular, but for long strings, regular performance may be a bit poor
function countOne(num){
//Num is a positive integer, the method is a bit violent
return Array.from({length:num},(v,i)=>i+1).join('').replace(/[^1]/g,'').length
}
console.log(countOne(400))Answer three
The following is the right answer. Convert each number into a string and count it1The number of
function getCount() {
let count = 0
for(let i=1;i<400;i++) {
count = count + `${i}`.split('1').length - 1
}
return count
}
//Output 180
console.log(getCount())Topic 3
Who is nostalgic? Who is nostalgic? The shadow makes the flower branch, the flower makes the shadow, the silk pulls the willow line, the willow pulls the silk. This is a palindrome poem, that is to say, every poem is read in the same way. The following question is a palindrome number, that is, the numbers read forward and backward are the same, for example11,1221,2112wait.
subject
Please print it out1 - 10000All palindrome numbers between. among1~9Because there is only one digit, it is not palindrome.
answer
Answer one
const palindrome = length => {
const res = []
const digits = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9']
const add = (current, length) => {
if (length <= 1) return
digits.forEach(digit => {
res.push(digit + current + digit)
add(digit + current + digit, length - 2)
})
}
digits.forEach(num => {
add(num, length - 1)
res.push(num + num)
add(num + num, length - 2)
})
return res.filter(num => !num.startsWith('0'))
}
//189 in total
console.log(palindrome(4))Answer two
function palindrome (max) {
return Array(max + 1).fill('').reduce((a, c, i) => {
if (i > 10) {
const arr = Array.from(`${i}`)
const [x, y] = [`${i}`, arr.reverse().join('')]
x === y && a.push(i)
}
return a
}, [])
}
//189 in total
console.log(palindrome(10000))Answer three
const result = [...Array(10000).keys()].filter((x) => x> 10 && x === Number(x.toString().split('').reverse().join('')) )
console.log(result)
Topic 4
subject
Please implement the function in the following codefnTo enable it to output the specifiedidCorresponding to all parentsidAnd itselfid
const data = [
{
id: 1,
name: '222',
children: [{
id: 2,
name: '34',
children: [{
id: 112,
name: '334',
}, {
id: 113,
name: '354',
}
]
}]
}
]
function fn(id) {
}
//Output [1, 2, 112]
console.log(fn(112))answer
Answer one
const data = [
{
id: 1,
name: '222',
children: [{
id: 2,
name: '34',
children: [{
id: 112,
name: '334',
}, {
id: 113,
name: '354',
}
]
}]
}
]
function fn(id) {
const res = []
const find = _ => {
if (!_) return
return _.find(item => (item.id === id || find(item.children)) && res.push(item.id))
}
find(data)
return res.reverse()
}
console.log(fn(112))
Answer two
const fn = (id, ancestors = [], current = data) => {
for (let i = 0; i < current.length; i++) {
if (current[i].id === id) return ancestors.concat(id)
if (current[i].children && current[i].children.length) {
const ret = fn(id, ancestors.concat(current[i].id), current[i].children)
if (ret) return ret
}
}
}
console.log(fn(112))
Answer three
function fn(id) {
const arr = []
const getIds = (ids) => {
for (const v of ids) {
arr.push(v.id)
if (v.id === id) {
return
} else if (v.children) {
getIds(v.children)
} else {
arr.pop()
}
}
}
getIds(data)
return arr
}
console.log(fn(112))
Topic 5
subject
Please implement the function toentryConvert tooutputData format for
const entry = {
'a.b.c.dd': 'abcdd',
'a.d.xx': 'adxx',
'a.e': 'ae'
}
//Request to be converted to the following object
const output = {
a: {
b: {
c: {
dd: 'abcdd'
}
},
d: {
xx: 'adxx'
},
e: 'ae'
}answer
Answer one
function transform(obj) {
const res = {}
for (let [keys, value] of Object.entries(obj)) {
keys
.split('.')
.reduce((prev, cur, idx, arr) =>
prev[cur] = prev[cur] || (arr[idx + 1] ? {} : value)
, res)
}
return res
}
Answer two
const transform = (input: { [P in string]: string }): Object => {
const ret = {}
Object.entries(input).forEach(([keys, val]) => {
let root = ret
keys.split('.').forEach((key, ind, arr) => {
if (ind === arr.length - 1) root[key] = val
else {
root[key] = root[key] || {}
root = root[key]
}
})
})
return ret
}
Answer three
const entry = {
'a.b.c.dd': 'abcdd',
'a.d.xx': 'adxx',
'a.e': 'ae',
}
const convert = (data) => {
let res = {}
const entries = Object.entries(data)
for (let i = 0; i < entries.length; i++) {
let temp = res
let [key, value] = entries[i]
const everyOne = key.split('.')
for (let j = 0; j < everyOne.length; j++) {
if (j === everyOne.length - 1) {
temp[everyOne[j]] = value
}
temp[everyOne[j]] = temp[everyOne[j]] || {}
temp = temp[everyOne[j]]
}
}
return res
}
console.log(convert(entry))
summary
These daily problems are some programming problems, some of which may be encountered in our daily development. By doing these problems, you can also test your mastery of these practical programming skills. The daily one comes from the official account [front end play], and the working day is pushed on time every day at eight forty every morning, every day, every day, growing a little bit every day.
epilogue
Don’t blow out your inspiration and imagination; don’t be a slave to your model. ——Vincent Van Gogh