How to Check if a JavaScript String Contains a Specific Text?

Using includes() to Check if a String Contains Text

The includes() method is the simplest and most readable way to determine whether a string contains another string.

Syntax

string.includes(searchString);

Example:

const technology = "Artificial Intelligence";

if (technology.includes("Intelligence")) {

console.log("The string contains the word.");

}

Output:

The string contains the word.

The method returns true if the substring exists and false otherwise.

const language = "JavaScript";

console.log(language.includes("Script"));

console.log(language.includes("Python"));

Output:

true

false

Is includes() Case-Sensitive?

Yes. JavaScript’s includes() method is case-sensitive.

For example:

const text = "JavaScript is popular.";

console.log(text.includes("JavaScript"));

console.log(text.includes("javascript"));

Output:

true

false

The capitalization differs between “JavaScript” and “javascript”.

How to Perform a Case-Insensitive Check

Convert both strings to lowercase before using includes():

const text = "JavaScript is popular.";

const searchText = "javascript";

const result = text.toLowerCase().includes(searchText.toLowerCase());

console.log(result);

Output:

true

This approach allows the comparison to ignore differences in capitalization.

Using indexOf() to Check if a String Contains Text

Before includes() became widely available, developers commonly used indexOf().

The method returns the position of the first occurrence of the specified substring. If the substring is not found, it returns -1.

const text = "Learn JavaScript programming.";

const position = text.indexOf("JavaScript");

console.log(position);

Output:

6

You can use this behavior to check whether a string contains a substring:

const text = "Learn JavaScript programming.";

if (text.indexOf("JavaScript") !== -1) {

console.log("Text found.");

}

Output:

Text found.

Although indexOf() is still useful, includes() is usually easier to read when you only need a Boolean result.

Using search() to Find Text

The search() method searches a string using a regular expression and returns the position of the first match.

const text = "JavaScript makes web development interactive.";

const position = text.search(/JavaScript/);

console.log(position);

Output:

0

If no match is found, search() returns -1.

const text = "JavaScript makes web development interactive.";

if (text.search(/development/) !== -1) {

console.log("Match found.");

}

Output:

Match found.

search() becomes especially useful when the search requires a regular expression rather than a simple substring.

Using match() to Check if a String Contains Text

The match() method can search a string using a regular expression.

const text = "Learning JavaScript is useful.";

const result = text.match(/JavaScript/);

console.log(result);

If a match exists, JavaScript returns a match object. If no match exists, it returns null.

You can use it in a conditional statement:

const text = "Learning JavaScript is useful.";

if (text.match(/JavaScript/)) {

console.log("JavaScript was found.");

}

Output:

JavaScript was found.

For simple substring checks, however, includes() is generally more straightforward.

Using Regular Expressions

Regular expressions are useful when you need more advanced matching rules.

For example, you can use the test() method to check whether a pattern exists:

const text = "The application uses JavaScript.";

const pattern = /JavaScript/;

console.log(pattern.test(text));

Output:

true

Case-Insensitive Regular Expression

The i flag makes the search case-insensitive.

const text = "The application uses JavaScript.";

const pattern = /javascript/i;

console.log(pattern.test(text));

Output:

true

Regular expressions are particularly useful when the search criteria are more complex than a fixed substring.