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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.

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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

Examples

Using includes()

const str = 'To be, or not to be, that is the question.'

console.log(str.includes('To be'))        // true
console.log(str.includes('question'))     // true
console.log(str.includes('nonexistent'))  // false
console.log(str.includes('To be', 1))     // false
console.log(str.includes('TO BE'))        // false
console.log(str.includes(''))             // true

Specifications

Specification
ECMAScript Language Specification # sec-string.prototype.includes

Browser compatibility

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet	Deno	Node.js
`includes`	41	12	40 18-48	No	28	9	41	41	40 18-48	28	9	4.0	1.0	4.0.0