object.js

module.exports = {
    isEmpty() {
        return this.keys().length == 0
    },
    uc(keys = []) {
        if (keys.isStr) keys = keys.arr()
        if (keys.length == 0) keys = this.keys()
        keys.forEach(k => this[k] = this[k].uc())
        return this
    },
    lc(keys = []) {
        if (keys.isStr) keys = keys.arr()
        if (keys.length == 0) keys = this.keys()
        keys.forEach(k => this[k] = this[k].lc())
        return this
    },
    tc(keys = []) {
        if (keys.isStr) keys = keys.arr()
        if (keys.length == 0) keys = this.keys()
        keys.forEach(k => this[k] = this[k].tc())
        return this
    },
    keys() {
        return Object.keys(this)
    },
    vals(fn) {
        if (!fn) return this.keys().map(k => this[k])
        this.keys().forEach(k => fn(this[k]))
    },
    slice(keys) {
        if (keys.isStr) keys = keys.arr()
        var r = (acc, k) => {
            if (k in this) acc[k] = this[k]
            return acc
        }
        return keys.reduce(r, {})
    },
    map(fn, acc = {}) {
        var r = (acc, k) => (fn(this, k, acc), acc)
        return this.keys().reduce(r, acc)
    },
    each(fn) {
        this.keys().forEach(k => fn(k, this))  
    },
    keyval(ks = '=', rs = '\n') {
        if (typeof ks == 'string') {
            var r = (o, k, acc) => {
                acc.push(k + ks + o[k])
                return acc
            }
            return this.map(r, []).join(rs)
        }
        else if (Array.isArray(ks)) {
            var [key, val] = ks
            var r = (o, k, acc) => {
                acc.push({[key || 'k']: k, [val || 'v']: o[k]})
                return acc
            }
            return this.map(r, [])    
        }
    },
    assign(...ls) {
        return Object.assign(this, ...ls)
    },
    concat(...ls) {
        return Object.assign({}, this, ...ls)
    },
    def(...ls) {
        return Object.assign({}, ...ls, this)
    },
    mv(o) {
        o.map((self, k, acc) => {
            if (o[k]) this[o[k]] = this[k]
            delete this[k]
        })
        return this
    },
    mvp(o) {
        return this.map((self, k, acc) => {
            if (k in o) {
                if (o[k]) acc[o[k]] = self[k]
            }
            else acc[k] = self[k]
        })
    },
    rm(...ls) {
        if (ls.length == 1) ls = ls[0].arr()
        ls.forEach(k => delete this[k])
        return this
    },
    rmp(...ls) {
        var ret = {}.concat(this)
        if (ls.length == 1) ls = ls[0].arr()
        ls.forEach(k => delete ret[k])
        return ret
    },
    notIn(o) {
        var ok = o.keys()
        return this.keys().filter(k => ok.indexOf(k) == -1)
    },
    getpath(path) {
        var {k, o} = mkpath(this, path)
        return o[k] 
    },
    setpath(path, v, noclobber = false) {
        var {k, o} = mkpath(this, path)
        if (!noclobber || !(k in o)) o[k] = v
        return o[k]
    },
    json(safe = false) {
        if (this instanceof Error) return JSON.stringify(this.obj())
        return safe ? safeJSON(this) : JSON.stringify(this)
    },
    tee(path) {
        JSON.stringify(this).tee(path, {clobber: true})
    }
}

function mkpath(o, path) {
    if (typeof(path) == 'string')
        path = path.replace(/\./g, '/').split('/')
    var k = path.pop()
    path.forEach(k => { if (!o[k]) o[k] = {}; o = o[k] })
    return {k, o}
}

// https://stackoverflow.com/questions/11616630/json-stringify-avoid-typeerror-converting-circular-structure-to-json

function safeJSON(v) {
    const cache = new Set()
    return JSON.stringify(v, function (key, value) {
      if (typeof value === 'object' && value !== null) {
        if (cache.has(value)) {
          // Circular reference found
          try {
            // If this value does not reference a parent it can be deduped
           return JSON.parse(JSON.stringify(value))
          }
          catch (err) {
            // discard key if value cannot be deduped
           return
          }
        }
        // Store value in our set
        cache.add(value)
      }
      return value
    })
  }