中划线字符转换为驼峰

##### 正则
```js
/-\w/g

```
##### 实战
```js
const camelCase = (str) => str.replace(/-\w/g, t => t.substr(1).toUpperCase())

const str = 'my-name-is-loadingmore'
const str2 = '-my-name-is-loadingmore'

camelCase(str) // myNameIsLoadingmore
camelCase(str2) // MyNameIsLoadingmore
```