switch语句

 var monthNum = prompt('请输入月份');
    var monthName;
    switch (monthNum) {
        case '1':
            monthName = '一月';
            break;
        case '2':
            monthName = '2月';
            break;
        case '3':
            monthName = '3月';
            break;
        case '4':
            monthName = '4月';
            break;
        case '5':
            monthName = '5月';
            break;
        case '6':
            monthName = '6月';
            break;
        case '7':
            monthName = '7月';
            break;
        case '8':
            monthName = '8月';
            break;
        case '9':
            monthName = '9月';
            break;
        case '10':
            monthName = '10月';
            break;
        case '11':
            monthName = '11月';
            break;
        case '12':
            monthName = '12月';
            break;
        default : 
            console.log('badinput');
    }   
    console.log(monthName);