var ScheduleTypeEnum = {
    IPI: {
        value: 'IPI',
        description: '等额本金'
    },
    EPI: {
        value: 'EPI',
        description: '等额本息'
    },
    IOI: {
        value: 'IOI',
        description: '一次还本按频率结息'
    },
    FPI: {
        value: 'FPI',
        description: '利随本清'
    },
    UDS: {
        value: 'UDS',
        description: '用户自定义还款计划'
    }
};
   function getDescriptionById(enums, id) {
    var description = '';
    for(var key in enums){
        if(enums[key].value != undefined && enums[key].value == id){
            description = enums[key].description;
        }
    }
    return description;
}
console.log(getDescriptionById(ScheduleTypeEnum,'FPI'));