code: function format(string) {
          string = string.toLowerCase().replace(/-(.)?/g, function ($0, $1) {
              return '-' + $1.toUpperCase();
          });
  
          return string.charAt(0).toUpperCase()
              + string.substring(1);
      }
docs: 格式化字符串
  content-type -> Content-Type
  
  @inner
  @param {string} string 字符串
  @return {string}