using-filter.js

function filterShortStateName(obj) {
    let array = obj.map(shortName => {
        if (shortName.length < 7) {
            return shortName
        }
        // console.log(shortName.length)
        return null
    })
    let arr = []
    arr = array.filter(function(s) {
        return s !== null
    })
    return arr
}

function filterStartVowel(obj) {
    let array = obj.map(vowel => {
        const regex = /^[aeiouAEIOU]/g
        const resRegex = new RegExp(regex)
        let str = vowel.match(resRegex)
        if (str !== null) {
            return vowel
        }
        return null
    })
    let arr = []
    arr = array.filter(function(s) {
        return s !== null
    })
    return arr
}

function filter5Vowels(obj) {
    let array = obj.map(vowels5 => {
        const regex = /[aeiouAEIOU]/g
        const resRegex = new RegExp(regex)
        let str = vowels5.match(resRegex)
        if (str.length >= 5) {
            return vowels5
        }
        return null
    })
    let arr = []
    arr = array.filter(function(s) {
        return s !== null
    })
    return arr
}

function filter1DistinctVowel(obj) {
    let array = obj.map(filter => {
        const regex = /[aeiouAEIOU]/g
        const resRegex = new RegExp(regex)
        let str = filter.match(resRegex)
        let arr = []
        let flag = false
        Loop:
            for (let i = 0; i < str.length - 1; i++) {
                for (let j = i + 1; j < str.length; j++) {
                    if (str[i].toUpperCase() !== str[j].toUpperCase()) {
                        flag - false
                        break Loop
                    }
                }
                flag = true
            }
        if (flag) {
            return filter
        }
        return null
    })
    let arr = []
    arr = array.filter(function(s) {
        return s !== null
    })
    return arr
}

function multiFilter(obj) {
    let array = obj.map(str => {
        let flagCapital = false
        let flagName = false
        let flagTag = false
        let flagRegion = false
        if (str.capital.length >= 8) {
            flagCapital = true
        }
        const regex = /^[aeiouAEIOU]/g
        const resRegex = new RegExp(regex)
        const regexT = /[aeiouAEIOU]/g
        const resRegexT = new RegExp(regexT)
        let res = str.name.match(resRegex)
        let resTag = str.tag.match(resRegexT)
        if (res === null) {
            flagName = true
        }
        if (resTag !== null) {
            flagTag = true
        }
        if (str.region !== 'South') {
            flagRegion = true
        }
        if (flagCapital && flagName && flagRegion && flagTag) {
            return str
        }
        return null
    })
    let arr = []
    arr = array.filter(function(s) {
        return s !== null
    })
    return arr
}
// console.log(multiFilter(arr2))