test2.jd

function subsetSum(arr, val, i = 0) {
    let r = []
    while (i < arr.length) {
        let v = arr[i]
        if (v == val)
            r.push(v)
        if (v < val)
            subsetSum(arr, val - v, i + 1).forEach((item) => {
                r.push(v + ',' + item)
            })
        i++
    }
    return r
}
​
export const ROLE_ALPHA = 1
export const ROLE_BETA = 2
export const ROLE_GAMMA = 4
export const ROLE_DELTA = 8
export const ROLE_EPSILON = 16
​
let roleNames= {}
​
function fetchRoleName(roleId) {
    return roleNames[roleId]
}
​
roleNames[ROLE_ALPHA]   = 'Alpha'
roleNames[ROLE_BETA]    = 'Bravo'
roleNames[ROLE_GAMMA]   = 'Charlie'
roleNames[ROLE_DELTA]   = 'Delta'
roleNames[ROLE_EPSILON] = 'Echo'

export default function (roles) {
    let roleName = ''
    let roles_arr = [
        ROLE_ALPHA,
        ROLE_BETA,
        ROLE_GAMMA,
        ROLE_DELTA,
        ROLE_EPSILON
    ]
    let roleIds = subsetSum(roles_arr, roles)
    if (typeof roleIds[0].length !== 'undefined' && roleIds[0].length > 0) {
        let roleIdsArr = roleIds[0].split(',')
        roleIdsArr.forEach((item) => {
            roleName = roleName + fetchRoleName(item) + ', '
        })
    } else {
        roleName = fetchRoleName(roleIds[0])
    }
    return roleName
}