core-js/internals/array-last-index-of.js

Standard library

'use strict';
var toIndexedObject = require('../internals/to-indexed-object');
var toInteger = require('../internals/to-integer');
var toLength = require('../internals/to-length');
var nativeLastIndexOf = [].lastIndexOf;

var NEGATIVE_ZERO = !!nativeLastIndexOf && 1 / [1].lastIndexOf(1, -0) < 0;
var SLOPPY_METHOD = require('../internals/sloppy-array-method')('lastIndexOf');

// `Array.prototype.lastIndexOf` method implementation
// https://tc39.github.io/ecma262/#sec-array.prototype.lastindexof
module.exports = (NEGATIVE_ZERO || SLOPPY_METHOD) ? 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 = Math.min(index, toInteger(arguments[1]));
  if (index < 0) index = length + index;
  for (;index >= 0; index--) if (index in O) if (O[index] === searchElement) return index || 0;
  return -1;
} : nativeLastIndexOf;