array-last-index-of.js

'use strict';
var toIndexedObject = require('../internals/to-indexed-object');
var toInteger = require('../internals/to-integer');
var toLength = require('../internals/to-length');
var arrayMethodIsStrict = require('../internals/array-method-is-strict');
var arrayMethodUsesToLength = require('../internals/array-method-uses-to-length');

var min = Math.min;
var nativeLastIndexOf = [].lastIndexOf;
var NEGATIVE_ZERO = !!nativeLastIndexOf && 1 / [1].lastIndexOf(1, -0) < 0;
var STRICT_METHOD = arrayMethodIsStrict('lastIndexOf');
// For preventing possible almost infinite loop in non-standard implementations, test the forward version of the method
var USES_TO_LENGTH = arrayMethodUsesToLength('indexOf', { ACCESSORS: true, 1: 0 });
var FORCED = NEGATIVE_ZERO || !STRICT_METHOD || !USES_TO_LENGTH;

// `Array.prototype.lastIndexOf` method implementation
// https://tc39.es/ecma262/#sec-array.prototype.lastindexof
module.exports = FORCED ? function lastIndexOf(searchElement /* , fromIndex = @[*-1] */) {
  // convert -0 to +0
  if (NEGATIVE_ZERO) return nativeLastIndexOf.apply(this, arguments) || 0;
  var O = toIndexedObject(this);
  var length = toLength(O.length);
  var index = length - 1;
  if (arguments.length > 1) index = min(index, toInteger(arguments[1]));
  if (index < 0) index = length + index;
  for (;index >= 0; index--) if (index in O && O[index] === searchElement) return index || 0;
  return -1;
} : nativeLastIndexOf;