Array.prototype[@@unscopables]

Властивості символа @@unscopable містять властивості імен, що не були включені в ECMAScript до версії ES2015. Ці властивості виключені з прив'язок оператора with.

Синтаксис

arr[Symbol.unscopables]

Опис

The default array properties that are excluded from with bindings are: copyWithin, entries, fill, find, findIndex, includes, keys, and values.

See Symbol.unscopables for how to set unscopables for your own objects.

Приклади

The following code works fine in ES5 and below. However, in ECMAScript 2015 and later, the Array.prototype.keys() method was introduced. That means that inside with environments, "keys" would now be the method and not the variable. This is where now the built-in @@unscopables Array.prototype[@@unscopables] symbol property comes into play and prevents that some of the Array methods are being scoped into the with statement.

var keys = [];

with (Array.prototype) {
  keys.push('something');
}

Object.keys(Array.prototype[Symbol.unscopables]); 
// ["copyWithin", "entries", "fill", "find", "findIndex", 
//  "includes", "keys", "values"]

Специфікації

Підтримка веб-переглядачами

Дивіться також

• Symbol.unscopables