Deprecation Guide for Enumerable#contains

The Enumerable#contains and Array#contains methods were deprecated in favor of Enumerable#includes and Array#includes to stay in line with ES standards. See RFC for details.

contains and includes have similar behaviors. A notable exception is how NaN values are handled. contains uses Strict equality comparison algorithm for testing inclusion while includes uses SameValueZero algorithm.

Before:

var arr = ['a', 'b', 'c', NaN, undefined, null];

arr.contains('b');        // true
arr.contains('d');        // false
arr.contains(NaN);        // false
arr.contains(null);       // false
arr.contains(undefined);  // false

After:

var arr = ['a', 'b', 'c', NaN, undefined, null];

arr.includes('b');        // true
arr.includes('d');        // false
arr.includes(NaN);        // true
arr.includes(null);       // true
arr.includes(undefined);  // true

includes also allows a second optional parameter startAt to specify the index at which to begin searching:

var arr = ['a', 'b', 'c', NaN];

arr.includes('c', 2);   // true
arr.includes('c', -2);  // true

Note that the second startAt parameter is only available for Ember.Array because Ember.Enumerable does not rely on index-ordered access.

Enumerable#without and MutableEnumerable#addObject use now internally includes instead of contains. This leads to some minor breaking changes:

Before:

var arr = ['a', 'b'];

arr.addObject(NaN);       // ['a', 'b', NaN]
arr.addObject(NaN);       // ['a', 'b', NaN, NaN]
arr.without(NaN);         // ['a', 'b', NaN, NaN]

After:

var arr = ['a', 'b'];

arr.addObject(NaN);       // ['a', 'b', NaN]
arr.addObject(NaN);       // ['a', 'b', NaN]
arr.without(NaN);         // ['a', 'b']

Addon authors should use ember-runtime-enumerable-includes-polyfill to fix the deprecation in a backwards-compatible way.

Added in PR #13553.