String.prototype.includes()

The includes() method of {{jsxref("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.

{{InteractiveExample("JavaScript Demo: String.prototype.includes()", "shorter")}}

```js interactive-example const sentence = "The quick brown fox jumps over the lazy dog.";

const word = "fox";

console.log( The word "${word}" ${ sentence.includes(word) ? "is" : "is not" } in the sentence, ); // Expected output: "The word "fox" is in the sentence"

## Syntax

```js-nolint
includes(searchString)
includes(searchString, position)

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 {{optional_inline}}
• : 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, including when searchString is an empty string; otherwise, false.

Exceptions#

• {{jsxref("TypeError")}}
• : Thrown 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#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

• Polyfill of String.prototype.includes in core-js
• es-shims polyfill of String.prototype.includes
• {{jsxref("Array.prototype.includes()")}}
• {{jsxref("TypedArray.prototype.includes()")}}
• {{jsxref("String.prototype.indexOf()")}}
• {{jsxref("String.prototype.lastIndexOf()")}}
• {{jsxref("String.prototype.startsWith()")}}
• {{jsxref("String.prototype.endsWith()")}}