code: function upperFirst(str) {
    if (!str) {
      return console.error('错误: upperFirst 方法需要传入字符串类型的值');
    }
    return str.charAt(0).toUpperCase() + str.slice(1);
  }
docs: 首字母大写
  @param {string} str
  @return {string}
  
  @example
  Handlebars.compile('{{upperFirst "abcDEF"}}')() // => "AbcDEF"
  Handlebars.compile('{{upperFirst "AbcDEF"}}')() // => "AbcDEF"
  Handlebars.compile('{{upperFirst "-abcDEF"}}')() // => "-abcDEF"
  Handlebars.compile('{{upperFirst "a"}}')() // => "A"
  Handlebars.compile('{{upperFirst ""}}')() // => ""