从事前端开发一年半，下面是我做的一份面试题，分享一下，
希望大家指出我实现过程中的不足。
/**
extensions is an Array and each item has such format:
{firstName: 'xxx', lastName: 'xxx', ext: 'xxx', extType: 'xxx'}
lastName, ext can be empty, extType can only has "DigitalUser", "VirtualUser","FaxUser","Dept","AO".
**/
/**
Question 1: sort extensions by "firstName" + "lastName" + "ext" ASC
**/
function sortExtensionsByName(extensions) {
// reserved the type of sort
let type = String(arguments[1]).toLowerCase() === 'desc' ? 'desc' : 'asc';
if (Array.isArray(extensions)) {
extensions.sort(function(a, b) {
let firstLength = Math.max(a.firstName.length, b.firstName.length),
lastLength = Math.max((a.lastName || '').length, (b.lastName || '').length),
extLength = Math.max((a.ext || '').length, (b.ext || '').length),
aStr,
bStr;
aStr = a.firstName.padEnd(firstLength, ' ') + (a.lastName || '').padEnd(lastLength, ' ') + (a.ext || '').padEnd(extLength, ' '),
bStr = b.firstName.padEnd(firstLength, ' ') + (b.lastName || '').padEnd(lastLength, ' ') + (b.ext || '').padEnd(extLength, ' ');
return type === 'asc' ? aStr.localeCompare(bStr) : bStr.localeCompare(aStr);
});
} else {
console.log("error: The first parameter should be an Array, e.g., [{firstName: 'xxx', lastName: 'xxx', ext: 'xxx', extType: 'xxx'}]");
}
}
/**
Question 2: sort extensions by extType follow these orders ASC
DigitalUser < VirtualUser < FaxUser < AO < Dept.
**/
function sortExtensionsByExtType(extensions) {
// reserved the type of sort
let type = String(arguments[1]).toLowerCase() === 'desc' ? 'desc' : 'asc',
sortObj = {
'Dept': 0,
'AO': 1,
'FaxUser': 2,
'VirtualUser': 3,
'DigitalUser': 4
};
if (Array.isArray(extensions)) {
extensions.sort(function(a, b) {
let aNum = sortObj[a.extType],
bNum = sortObj[b.extType];
return type === 'asc' ? aNum - bNum : bNum - aNum;
});
} else {
console.log("error: The first parameter should be an Array, e.g., [{firstName: 'xxx', lastName: 'xxx', ext: 'xxx', extType: 'xxx'}]");
}
}
/**
saleItems is an Array has each item has such format:
{
month: n, //[1-12],
date: n, //[1-31],
transationId: "xxx",
salePrice: number
}
**/
/**
Question 3: write a function to calculate and return a list of total sales (sum) for each quarter, expected result like:
[
{quarter: 1, totalPrices: xxx, transactionNums: n},
{....}
]
**/
function sumByQuarter(saleItems) {
let list = [
{quarter: 1, totalPrices: 0, transactionNums: 0},
{quarter: 2, totalPrices: 0, transactionNums: 0},
{quarter: 3, totalPrices: 0, transactionNums: 0},
{quarter: 4, totalPrices: 0, transactionNums: 0}
];
if (Array.isArray(saleItems)) {
saleItems.forEach(function(item) {
let totalItem = {},
num = item.salePrice,
totalNum = 0,
baseNum1 = 0,
baseNum2 = 0,
baseNum = 0;
if(item.month < 4) {
totalItem = list[0];
} else if (item.month < 7) {
totalItem = list[1];
} else if (item.month < 10) {
totalItem = list[2];
} else {
totalItem = list[3];
}
totalItem.transactionNums++;
totalNum = totalItem.totalPrices;
// precision handling
try {
baseNum1 = num.toString().split(".")[1].length;
} catch (e) {
baseNum1 = 0;
}
try {
baseNum2 = totalNum.toString().split(".")[1].length;
} catch (e) {
baseNum2 = 0;
}
baseNum = Math.pow(10, Math.max(baseNum1, baseNum2));
totalItem.totalPrices = (num * baseNum + totalNum * baseNum) / baseNum;
});
} else {
console.log(`
error: The first parameter should be an Array, e.g.,
[
{
month: n, //[1-12],
date: n, //[1-31],
transationId: "xxx",
salePrice: number
}
]
`);
}
return list;
}
/**
Question 4: write a function to calculate and return a list of average sales for each quarter, expected result like:
[
{quarter: 1, averagePrices: xxx, transactionNums: n},
{....}
]
**/
function averageByQuarter(saleItems) {
// reused the 'sumByQuarter'
let list = sumByQuarter(saleItems);
list.forEach(function(item) {
let num = item.totalPrices,
totalNum = item.transactionNums,
baseNum = 0;
if(totalNum === 0) {
item.averagePrices = 0;
} else {
// precision handling
try {
baseNum = num.toString().split(".")[1].length;
} catch (e) {
baseNum = 0;
}
item.averagePrices = (Number(num.toString().replace(".", "")) / totalNum) / Math.pow(10, baseNum);
}
delete item.totalPrices;
});
return list;
}
/**
Question 5: please create a tool to generate Sequence
Expected to be used like:
var sequence1 = new Sequence();
sequence1.next() --> return 1;
sequence1.next() --> return 2;
in another module:
var sequence2 = new Sequence();
sequence2.next() --> 3;
sequence2.next() --> 4;
**/
// ES5
var Sequence;
(function(){
var unique;
Sequence = function(){
if(unique){
return unique
}
unique = this;
this.index = 1;
this.next = function() {
return this.index++;
};
}
}());
// ES6
class Sequence {
next() {
return Sequence.index++;
}
}
Sequence.index = 1;
/**
Question 6:
AllKeys: 0-9;
usedKeys: an array to store all used keys like [2,3,4];
We want to get an array which contains all the unused keys,in this example it would be: [0,1,5,6,7,8,9]
**/
function getUnUsedKeys(allKeys, usedKeys) {
//TODO
if (Array.isArray(allKeys) && Array.isArray(usedKeys)) {
let newArr = allKeys.concat(usedKeys),
unusedKeys = [];
// sort the values, and then remove duplicate values in loop
newArr.sort();
for(let i = 0; i < newArr.length; i++){
if(newArr[i] !== newArr[i+1]) {
unusedKeys.push(newArr[i]);
} else {
i++;
}
}
return unusedKeys;
} else {
console.log('error: The first parameter and the second parameter should be an Array');
}
}
欢迎来到这里！
我们正在构建一个小众社区，大家在这里相互信任，以平等 • 自由 • 奔放的价值观进行分享交流。最终，希望大家能够找到与自己志同道合的伙伴，共同成长。
注册 关于