Get the Number from the End of a String in JavaScript

Get the Number from the End of a String #

To get the number from the end of a string, call the match() method, passing it the following regular expression [0-9]+$. The match method will return an array containing the number from the end of the string at index 0.

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const str = 'one 2 three 456';

const arr = str.match(/[0-9]+$/);
console.log(arr); // 👉️ ['456']

const num = parseInt(arr[0], 10);
console.log(num); // 👉️ 456

We used the String.match method to get an array containing the number at the end of a string.

The only parameter the method takes is a regular expression.

The forward slashes / / mark the beginning and end of the regular expression.

The square brackets [] part is called a character class and matches a range of digits from 0 to 9.

The dollar sign $ matches the end of the input.

If you ever need help reading a regular expression, check this regex cheatsheet from MDN out.

Once we have the array containing the digits match, we use the parseInt function to parse the string into a number.

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const str = 'one 2 three 456 seven';

const arr = str.match(/[0-9]+$/);
console.log(arr); // 👉️ null

If you need to handle this scenario, you can use an if statement.

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const str = 'one 2 three 456 seven';

const arr = str.match(/[0-9]+$/);
console.log(arr); // 👉️ null

let num;
if (arr !== null) {
  console.log('✅ String contains digits at the end');
  num = parseInt(arr[0], 10);
} else {
  console.log('⛔️ String contains NO digits at the end');
}

In this example, we only call the parseInt function, if we are sure the string contains digits at the end.

Trying to access the element at index 0 on a null value would give us an error, so it's good to handle these scenarios.

Further Reading #

• Replace the First Occurrence of Character in String in JS
• Get the First Number in a String using JavaScript