String.prototype.includes()

The includes() method performs a case-sensitive search to determine whether one string may be found within another string, returning true or false as appropriate.

Syntax

includes(searchString)
includes(searchString, position)

Parameters

• searchString
  • : A string to be searched for within str. Cannot be a regex.
• position optional
  • : The position within the string at which to begin searching for searchString. (Defaults to 0.)

Return value

true if the search string is found anywhere within the given string; otherwise, false if not.

Exceptions

• TypeError
  • : If searchString is a regex.

Description

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

Case-sensitivity

The includes() method is case sensitive. For example, the following expression returns false:

"Blue Whale".includes("blue"); // returns false

You can work around this constraint by transforming both the original string and the search string to all lowercase:

"Blue Whale".toLowerCase().includes("blue"); // returns true