# 6kyu

## 函数的连续调用

> 将字符串使用空格进行连接
>
> createMessage("Hello")("World!")("how")("are")("you?")() === "Hello World! how are you?"

函数中返回一个匿名函数，匿名函数调用父函数实现层级的调用，感觉类似递归的思想

```javascript
function createMessage(str) {
    return function(next){
      if (next === undefined) {return str;}
      return createMessage(str + " "+ next);
    }
}
```

## 两个数组去重

```javascript
## 遍历b来除去a中相同的
function array_diff(a, b) {
  b.map(function(item){
    if(a.indexOf(item)!=-1){
    while(a.indexOf(item)!=a.lastIndexOf(item)){
      a.splice(a.indexOf(item),1)
    }
    a.splice(a.indexOf(item),1)}
  })
  return a
}
```

秀儿

```javascript
## 之间遍历a
function array_diff(a, b) {
  return a.filter(function(x) { return b.indexOf(x) == -1; });
}
```

## 检测网址的主域名

输入数据如下,这次我也成为了秀儿的一员 hh

```javascript
domainName("http://github.com/carbonfive/raygun") == "github" 
domainName("http://www.zombie-bites.com") == "zombie-bites"
domainName("https://www.cnet.com") == "cnet"
```

```javascript
function domainName(url){
  return url.replace(/(https?:\/\/)?(www\.)?/,"").split("/")[0].split("\.")[0]
}
```


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