Symbol.match well-known symbol specifies the matching of a regular expression against a string. This function is called by the
This function is also used to identify if objects have the behavior of regular expressions. For example, the methods
String.prototype.includes(), check if their first argument is a regular expression and will throw a
TypeError if they are. Now, if the
match symbol is set to
false (or a Falsy value), it indicates that the object is not intended to be used as a regular expression object.
|Property attributes of
The following code will throw a
'/bar/'.startsWith(/bar/); // Throws TypeError, as /bar/ is a regular expression // and Symbol.match is not modified.
However, if you set
isRegExp check (that uses the
match property) will indicate that the object is not a regular expression object. The methods
endsWith won't throw a
TypeError as a consequence.
const re = /foo/; re[Symbol.match] = false; '/foo/'.startsWith(re); // true '/baz/'.endsWith(re); // false
|ECMAScript Language Specification |
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