array.js

module.exports = {
    lc() {
        return this.map(o => o.lc())
    },
    uc() {
        return this.map(o => o.uc())
    },
    unique() { 
        return this.filter((e, pos) => this.indexOf(e) == pos)
    },
    trim(nonempty = false) {
        var ret = this
        if (nonempty) ret = ret.filter(s => !!s)
        return ret.map(s => typeof s == 'string' ? s.trim() : s)
    },
    flat(depth = 1) {
        var r = (ret, v) => ret.concat(Array.isArray(v) && depth > 0 ? v.flat(depth - 1) : v)
        return this.reduce(r, [])
    },
    last(n = 0) {
        return this[this.length - (n + 1)]
    },
    unpack() {
        var l = this.length
        return l == 1 ? this[0] 
            : l == 0 && arguments.length > 0
            ? undefined
            : this
    },
    keyval(key = 'k', val = 'v') {
        var r = (acc, v) => {
            propadd(acc, v[key], v[val]); return acc 
        }
        return this.reduce(r, {})
    },
    indexOfObj(filter) {
        var ret = -1
        this.some((o,i) => {
            if (filter(o)) ret = i
        })
        return ret
    },
    json() {
        return JSON.stringify(this)
    },
    item(key, val) {
        if ((key || val) == undefined) return
        var r = this.filter(o => {
            var v = o[key]
            if (val instanceof RegExp) {
                if (typeof v != 'string') v = v.toString()
                return v.match(val)
            }
            else
                return v == val
        })
        return r[0] 
    },
    contains(v) {
        return this.indexOf(v) > -1
    },
    split(n) {
        if (!n) return this
        var ret = []
        for (var i = 0; i < this.length; i++) {
            let j = Math.floor(i / n)
            if (!ret[j]) ret[j] = []
            ret[j].push(this[i])
        }
        return ret
    },
    dict(nms) {
        var i = 0
        if (nms.isStr) nms = nms.arr()
        var fn = (o, v) => (o[nms[i++] || i] = v, o)
        var n = nms.length
        if (nms[n-1] == '*') {
            n = this.length; nms.pop()
        }
        return this.slice(0, n).reduce(fn, {})
    }
}

function propadd(o, k, v) {
    if (k in o) {
        if (Array.isArray(o[k])) o[k].push(v)
        else o[k] = [o[k], v]
    }
    else o[k] = v
}