前端面试题：驼峰体与匈牙利语法的相互转换

/* 
            驼峰体转匈牙利
        */
        function TfToXyl(params) {
            if (typeof params === 'string') {
                let reg = /^[A-Z]+$/
                let strArr = params.split('')
                let result;
                for (let i = 0; i < strArr.length; i++) {
                    if (reg.test(strArr[i]) === true) {
                        strArr[i] = `_${strArr[i].toLowerCase()}`
                    }
                }
                result = strArr.join('').slice(1)
                return result
            } else {
                throw new Error(`${params} is not a string`)
            }
        }

/* 
           匈牙利转驼峰体
        */
        function xylToTf(params) {
            if (typeof params === 'string') {
                let result = [];
                params.split('_').forEach(e => {
                    e = `${e.charAt(0).toUpperCase()}${e.slice(1)}`
                    result.push(e)
                })
                result = result.join('')
                return result
            } else {
                throw new Error(`${params} is not a string`)
            }
        }