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Vanilla JavaScript string includes

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Lets see how we can determine if a string contains a substring in JavaScript

10 May, 2020 · 2 min read

While we recently checked if a string startsWith or a string endsWith a specific substring, today we will learn how to find out if a string includes another substring.

To do so, we are using the JavaScript function includes().

JavaScript includes() function

We can use the includes() function by calling it on a string and passing a substring to it:

const string =
  'The greatest glory in living lies not in never falling, but in rising every time we fall.';

// Check if it includes with `living`
console.log(string.includes('living'));
// true

It is important for the includes() function to know that it is a case-sensitive function. So the following code will fail:

const string =
  'The greatest glory in living lies not in never falling, but in rising every time we fall.';

// Check if it includes with `Living`
console.log(string.includes('Living'));
// false

String includes with offset position parameter

As the brothers startsWith() and endsWith(), this has another position parameter. This position is from where it will start to look.

const string =
  'The greatest glory in living lies not in never falling, but in rising every time we fall.';

// Check if it includes with `living`
console.log(string.includes('living', 30));
// false

See the code examples in this Codepen

Feel free to play with the code here:

See the Pen Vanilla JavaScript string includes by Chris Bongers (@rebelchris) on CodePen.

Browser Support

This function works well in all modern browsers, including edge!

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