DESCRIPTION

Write a function that accepts an array of 10 integers (between 0 and 9), that returns a string of those numbers in the form of a phone number.

Example

createPhoneNumber([1, 2, 3, 4, 5, 6, 7, 8, 9, 0]) // => returns "(123) 456-7890"

The returned format must be correct in order to complete this challenge.

Don’t forget the space after the closing parentheses!

SOLUTION

• 方法一：数组的 slice() 方法

1
2
3
4
5
6
7
8
9
10
11

function createPhoneNumber(numbers) {
  // Create an array of the different parts of the phone number
  const areaCode = `(${numbers.slice(0, 3).join("")})`;
  const prefix = numbers.slice(3, 6).join("");
  const suffix = numbers.slice(6, 10).join("");

  // Combine the parts into the final phone number string
  const phoneNumber = `${areaCode} ${prefix}-${suffix}`;

  return phoneNumber;
}

DESCRIPTION

Your goal in this kata is to implement a difference function, which subtracts one list from another and returns the result.

It should remove all values from list a, which are present in list b keeping their order.

arrayDiff([1,2],[1]) == [2]

If a value is present in b, all of its occurrences must be removed from the other:

arrayDiff([1,2,2,2,3],[2]) == [1,3]

SOLUTION

• 方法一：

1
2
3

function arrDiff(a, b) {
  return a.filter((item) => !b.includes(item));
}

DESCRIPTION

Given an integral number, determine if it’s a square number:

In mathematics, a square number or perfect square is an integer that is the square of an integer; in other words, it is the product of some integer with itself.

The tests will always use some integral number, so don’t worry about that in dynamic typed languages.

Examples

1
2
3
4
5
6

-1  =>  false
 0  =>  true
 3  =>  false
 4  =>  true
25  =>  true
26  =>  false

SOLUTION

• 方法一：

1
2
3
4
5
6

var isSquare = function (n) {
  // 求平方根并取整
  let roundSqrt = Math.round(Math.sqrt(n));
  // 判断平方根相乘的结果是否与传入的数值相等
  return n === roundSqrt * roundSqrt;
};

DESCRIPTION

In this kata you will create a function that takes a list of non-negative integers and strings and returns a new list with the strings filtered out.

Example

1
2
3

filter_list([1, 2, "a", "b"]) == [1, 2];
filter_list([1, "a", "b", 0, 15]) == [1, 0, 15];
filter_list([1, 2, "aasf", "1", "123", 123]) == [1, 2, 123];

SOLUTION

• 数组的 filter() 方法

1
2
3
4

function filter_list(l) {
  // Return a new array with the strings filtered out
  return l.filter((word) => typeof word === "number");
}

DESCRIPTION

Trolls are attacking your comment section!

A common way to deal with this situation is to remove all of the vowels from the trolls’ comments, neutralizing the threat.

Your task is to write a function that takes a string and return a new string with all vowels removed.

For example, the string “This website is for losers LOL!” would become “Ths wbst s fr lsrs LL!”.

Note: for this kata y isn’t considered a vowel.

SOLUTION

• 方法一：字符串的 replace() 和 replaceAll() 方法都可，这两个方法都是返回一个新的字符串。

replace() 字符串模式只会被替换一次。要执行全局搜索和替换，请使用带有 g 标志的正则表达式或使用 replaceAll()。

1
2
3
4
5
6

function disemvowel(str) {
  let regex = /aeiou/gi;
  let result = str.replace(regex, "");
  // let result = str.replaceAll(regex, "");
  return result;
}