selectn
Version:
Curried property accessor function that resolves deeply-nested object properties via dot/bracket-notation string path while mitigating TypeErrors via friendly and composable API.
38 lines (32 loc) • 1.05 kB
JavaScript
const curry2 = require('curry2')
const dotted = require('brackets2dots')
const splits = require('dotsplit.js')
const string = Object.prototype.toString
module.exports = curry2(selectn)
/**
* Curried property accessor function that resolves deeply-nested object properties via dot/bracket-notation
* string path while mitigating `TypeErrors` via friendly and composable API.
*
* @param {String|Array} path
* Dot/bracket-notation string path or array.
*
* @param {Object} object
* Object to access.
*
* @return {Function|*|undefined}
* (1) returns `selectn/1` when partially applied.
* (2) returns value at path if path exists.
* (3) returns undefined if path does not exist.
*/
function selectn (path, object) {
let idx = -1
const seg = string.call(path) === '[object Array]' ? path : splits(dotted(path))
const end = seg.length
let ref = end ? object : undefined
while (++idx < end) {
if (Object(ref) !== ref) return undefined
ref = ref[seg[idx]]
}
return typeof ref === 'function' ? ref() : ref
}