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使用 reduce 减少一个额外声明的变量 #5

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使用 reduce 减少一个额外声明的变量 #5

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11 changes: 5 additions & 6 deletions README.md
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Expand Up @@ -112,18 +112,17 @@ Demo: https://www.etherdream.com/FunnyScript/cpu-hog/
一种统计 key 的个数，无需使用判断的写法：

```js
const map = {}
const str = 'hello world'

str.split('').forEach(key => {
map[key] = -~map[key]
})
const map = str.split('').reduce((prev, next) => {
prev[next] = -~prev[next];
return prev;
}, {});

console.log(map)
// {" ": 1, d: 1, e: 1, h: 1, l: 3, o: 2, r: 1, w: 1}
```

Demo: https://jsbin.com/lumexovida/edit?js,console,output
Demo: https://jsbin.com/cudarij/edit?js,console,output

> ~i = -(i + 1)，~undefined = -1

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