lodash/internal/isIterateeCall.js

var isIndex = require('./isIndex'),
    isLength = require('./isLength'),
    isObject = require('../lang/isObject');

/**
 * Checks if the provided arguments are from an iteratee call.
 *
 * @private
 * @param {*} value The potential iteratee value argument.
 * @param {*} index The potential iteratee index or key argument.
 * @param {*} object The potential iteratee object argument.
 * @returns {boolean} Returns `true` if the arguments are from an iteratee call, else `false`.
 */
function isIterateeCall(value, index, object) {
  if (!isObject(object)) {
    return false;
  }
  var type = typeof index;
  if (type == 'number') {
    var length = object.length,
        prereq = isLength(length) && isIndex(index, length);
  } else {
    prereq = type == 'string' && index in object;
  }
  if (prereq) {
    var other = object[index];
    return value === value ? value === other : other !== other;
  }
  return false;
}

module.exports = isIterateeCall;