ramda.prop/prop.js

R.prop exported as a module

//  Ramda v0.26.1
//  https://github.com/ramda/ramda
//  (c) 2013-2019 Scott Sauyet, Michael Hurley, and David Chambers
//  Ramda may be freely distributed under the MIT license.

(function (global, factory) {
  typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
  typeof define === 'function' && define.amd ? define(['exports'], factory) :
  (factory((global.R = {})));
}(this, (function (exports) { 'use strict';

  function _isPlaceholder(a) {
    return a != null &&
           typeof a === 'object' &&
           a['@@functional/placeholder'] === true;
  }

  /**
   * Optimized internal one-arity curry function.
   *
   * @private
   * @category Function
   * @param {Function} fn The function to curry.
   * @return {Function} The curried function.
   */
  function _curry1(fn) {
    return function f1(a) {
      if (arguments.length === 0 || _isPlaceholder(a)) {
        return f1;
      } else {
        return fn.apply(this, arguments);
      }
    };
  }

  /**
   * Optimized internal two-arity curry function.
   *
   * @private
   * @category Function
   * @param {Function} fn The function to curry.
   * @return {Function} The curried function.
   */
  function _curry2(fn) {
    return function f2(a, b) {
      switch (arguments.length) {
        case 0:
          return f2;
        case 1:
          return _isPlaceholder(a)
            ? f2
            : _curry1(function(_b) { return fn(a, _b); });
        default:
          return _isPlaceholder(a) && _isPlaceholder(b)
            ? f2
            : _isPlaceholder(a)
              ? _curry1(function(_a) { return fn(_a, b); })
              : _isPlaceholder(b)
                ? _curry1(function(_b) { return fn(a, _b); })
                : fn(a, b);
      }
    };
  }

  /**
   * Determine if the passed argument is an integer.
   *
   * @private
   * @param {*} n
   * @category Type
   * @return {Boolean}
   */
  var _isInteger = Number.isInteger || function _isInteger(n) {
    return (n << 0) === n;
  };

  function _isString(x) {
    return Object.prototype.toString.call(x) === '[object String]';
  }

  /**
   * Returns the nth element of the given list or string. If n is negative the
   * element at index length + n is returned.
   *
   * @func
   * @memberOf R
   * @since v0.1.0
   * @category List
   * @sig Number -> [a] -> a | Undefined
   * @sig Number -> String -> String
   * @param {Number} offset
   * @param {*} list
   * @return {*}
   * @example
   *
   *      const list = ['foo', 'bar', 'baz', 'quux'];
   *      R.nth(1, list); //=> 'bar'
   *      R.nth(-1, list); //=> 'quux'
   *      R.nth(-99, list); //=> undefined
   *
   *      R.nth(2, 'abc'); //=> 'c'
   *      R.nth(3, 'abc'); //=> ''
   * @symb R.nth(-1, [a, b, c]) = c
   * @symb R.nth(0, [a, b, c]) = a
   * @symb R.nth(1, [a, b, c]) = b
   */
  var nth = _curry2(function nth(offset, list) {
    var idx = offset < 0 ? list.length + offset : offset;
    return _isString(list) ? list.charAt(idx) : list[idx];
  });

  /**
   * Retrieve the value at a given path.
   *
   * @func
   * @memberOf R
   * @since v0.2.0
   * @category Object
   * @typedefn Idx = String | Int
   * @sig [Idx] -> {a} -> a | Undefined
   * @param {Array} path The path to use.
   * @param {Object} obj The object to retrieve the nested property from.
   * @return {*} The data at `path`.
   * @see R.prop, R.nth
   * @example
   *
   *      R.path(['a', 'b'], {a: {b: 2}}); //=> 2
   *      R.path(['a', 'b'], {c: {b: 2}}); //=> undefined
   *      R.path(['a', 'b', 0], {a: {b: [1, 2, 3]}}); //=> 1
   *      R.path(['a', 'b', -2], {a: {b: [1, 2, 3]}}); //=> 2
   */
  var path = _curry2(function path(paths, obj) {
    var val = obj;
    var idx = 0;
    var p;
    while (idx < paths.length) {
      if (val == null) {
        return;
      }
      p = paths[idx];
      val = _isInteger(p) ? nth(p, val) : val[p];
      idx += 1;
    }
    return val;
  });

  /**
   * Returns a function that when supplied an object returns the indicated
   * property of that object, if it exists.
   *
   * @func
   * @memberOf R
   * @since v0.1.0
   * @category Object
   * @typedefn Idx = String | Int
   * @sig Idx -> {s: a} -> a | Undefined
   * @param {String|Number} p The property name or array index
   * @param {Object} obj The object to query
   * @return {*} The value at `obj.p`.
   * @see R.path, R.nth
   * @example
   *
   *      R.prop('x', {x: 100}); //=> 100
   *      R.prop('x', {}); //=> undefined
   *      R.prop(0, [100]); //=> 100
   *      R.compose(R.inc, R.prop('x'))({ x: 3 }) //=> 4
   */

  var prop = _curry2(function prop(p, obj) { return path([p], obj); });

  exports.prop = prop;

  Object.defineProperty(exports, '__esModule', { value: true });

})));