这里指的遍历方法包括：map、reduce、reduceRight、forEach、filter、some、every 因为最近要进行了一些数据汇总，node版本已经是8.11.1了，所以直接写了个async/await的脚本。但是在对数组进行一些遍历操作时，发现有些遍历方法对Promise的反馈并不是我们想要的结果。

当然，有些严格来讲并不能算是遍历，比如说some，every这些的。
但确实，这些都会根据我们数组的元素来进行多次的调用传入的回调。

这些方法都是比较常见的，但是当你的回调函数是一个Promise时，一切都变了。

2018年五月书单～

1. 原理

Vue的双线数据绑定的原理主要是通过Object对象的defineProperty属性，重写data的set和get函数来实现的，这里通过一个实例来说明。主要实现v-model，v-bind和v-click三个命令，其他命令也可以自行补充。

Fizz Buzz

Write a program that outputs the string representation of numbers from 1 to n.

But for multiples of three it should output “Fizz” instead of the number and for the multiples of five output “Buzz”. For numbers which are multiples of both three and five output “FizzBuzz”.

Example:

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2
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4
5
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7
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9
10
11
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15
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n = 15,

Return:
[
    "1",
    "2",
    "Fizz",
    "4",
    "Buzz",
    "Fizz",
    "7",
    "8",
    "Fizz",
    "Buzz",
    "11",
    "Fizz",
    "13",
    "14",
    "FizzBuzz"
]

Find th Difference

Given two strings s and t which consist of only lowercase letters.

String t is generated by random shuffling string s and then add one more letter at a random position.

Find the letter that was added in t.

Example:

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Input:
s = "abcd"
t = "abcde"

Output:
e

Explanation:
'e' is the letter that was added.