HTML DOMTokenList supports()

Check if "allow-forms" is supported:

const list = element.sandbox;
list.supports("allow-forms");

Check if "allow-nonsense" is supported:

const list = element.sandbox;
list.supports("allow-nonsense");

Description

The supports() method returns true if a token in a DOMTokenList is one of the attribute's supported tokens.

domtokenlist.supports(token)

Parameter	Description
token	Required. The token to check for.

Type	Description
Boolean	`true` if the token is supported, otherwise `false`.

domtokenlist.supports() is a DOM Level 4 (2015) feature.

It is supported in all modern browsers:


Chrome	Edge	Firefox	Safari	Opera
Yes	Yes	Yes	Yes	Yes

domtokenlist.supports() is not supported in Internet Explorer 11 (or earlier).