String.prototype.includes()

The includes() method of String values performs a case-sensitive search to determine whether a given string may be found within this string, returning true or false as appropriate.

This method lets you determine whether or not a string includes another string.

Return value: true if the search string is found anywhere within the given string, including when searchString is an empty string; otherwise, false.

Parameters: searchString A string to be searched for within str. Cannot be a regex. All values that are not regexes are coerced to strings, so omitting it or passing undefined causes includes() to search for the string “undefined”, which is rarely what you want. position The position within the string at which to begin searching for searchString. (Defaults to 0.)

Syntax example: includes(searchString)